Magneto-resistance effect element

ABSTRACT

A method for manufacturing a magneto-resistance effect element includes: forming a first magnetic layer; forming a first metallic layer, on the first magnetic layer, mainly containing an element selected from the group consisting of Cu, Au, Ag; forming a functional layer, on the first metallic layer, mainly containing an element selected from the group consisting of Si, Hf, Ti, Mo, W, Nb, Mg, Cr and Zr; forming a second metallic layer, on the functional layer, mainly containing Al; treating the second metallic layer by means of oxidizing, nitriding or oxynitiriding so as to form a current confined layer including an insulating layer and a current path with a conductor passing a current through the insulating layer; and forming, on the current confined layer, a second magnetic layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 11/802,474,filed May 23, 2007, which is based upon and claims the benefit ofpriority from the prior Japanese Patent Application No. 2006-188711,filed on Jul. 7, 2006. The entire contents of each of these applicationsare incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for manufacturing amagneto-resistance effect element which is configured such that acurrent is flowed in the direction perpendicular to the film surfacethereof to detect the magnetization of the element and themagneto-resistance effect element.

2. Description of the Related Art

Recently, the miniaturization and the high density recording of a harddisk drive (HDD) is remarkably required and being progressed. In thefuture, it is promised to much develop the high density recording of theHDD. The HDD of high density recording can be realized by narrowing therecording track width. However, the amplitude of the magnetizationrelating to the recording, that is, the recording signal may be loweredas the track width is narrowed, so that it is required that thereproducing sensitivity of the MR head for reproducing the medium signalis enhanced.

Recently, a GMR (Giant Magneto-Resistance effect) head with a highsensitive spin valve film using the GMR film is employed. The “spinvalve” film has such a structure as sandwiching a non-magnetic metalspacer layer between two ferromagnetic layers. The stacking layercomponent structure exhibiting the change in resistance may be called asa “spin dependent scattering unit”. The magnetization of oneferromagnetic layer (often called as a “pinning layer” or “fixedmagnetization layer) is fixed by the magnetization of ananti-ferromagnetic layer and the magnetization of the otherferromagnetic layer (often called as a “free layer” or “freemagnetization layer”) is rotated in accordance with an external magneticfield. With the spin valve film, the intended large magneto-resistanceeffect can be obtained when the relative angle between the pinning layerand the free layer is changed.

A conventional spin valve film is formed as a CIP (Current In Plane)-GMRelement, a CPP (Current Perpendicular to Plane)-GMR element and a TMR(Tunneling Magneto-Resistance) element. With the CIP-GMR element, asense current is flowed along the film surface of the spin valve film.With the CPP-GMR element or the TMR element, a sense current is flowedin the direction perpendicular to the film surface thereof.

With the element which is utilized by flowing the sense current in thedirection perpendicular to the film surface, the spacer layer is made ofan insulating layer in the TMR element and of a metallic layer in theCPP-GMR element.

Herein, a metal CPP-GMR element of which the spin valve film is made ofa metallic layer has a smaller change in resistance to render thedetection of minute magnetic field difficult.

A CPP element with an oxide layer containing current confined paths inthe thickness direction thereof, which is called as an “NOL (nano-oxidelayer)”, is proposed (refer to Document 1). With the CPP element, bothof the element resistance and the MR ratio can be increased due to thecurrent confined to path (CCP) effect. Hereinafter, the element iscalled as a“CCP-CPPelement”.

[Document No. 1] JP-A 2002-208744 (KOKAI)

Such a magnetic recording device as the HDD is widely available for apersonal computer, a portable music player and the like. In the future,however, the reliability of the magnetic recording device is severelyrequired when the usage of the magnetic recording device is increasedand the high density recording is also developed. It is required, forexample, that the reliability of the magnetic recording device isdeveloped under a high temperature condition or a high speed operation.In this point of view, it is desired to much develop the reliability ofthe magnetic head in comparison with the conventional one.

Particularly, since the CCP-CPP element has a smaller resistance thanthe one of the conventional TMR element, the CCP-CPP element can beapplied for a high end magnetic recording device of server enterpriserequiring higher transfer rate. In the use of the high end magneticrecording device, both of the high density recording and the highreliability must be satisfied. Also, the high reliability under a highertemperature condition must be preferably satisfied. In other words, theCCP-CPP element is required to be used under the more severe condition(e.g., high temperature condition) and the more severe operation (e.g.,the information being read out while the magnetic disk is rotated athigh speed).

BRIEF SUMMARY OF THE INVENTION

An aspect of the present invention relates to a method for manufacturinga magneto-resistance effect element, including: forming a first magneticlayer; forming a first metallic layer, on the first magnetic layer,mainly containing an element selected from the group consisting of Cu,Au, Ag; forming a functional layer, on the first metallic layer, mainlycontaining an element selected from the group consisting of Si, Hf, Ti,Mo, W, Nb, Mg, Cr and Zr; forming a second metallic layer, on thefunctional layer, mainly containing Al; treating the second metalliclayer by means of oxidizing, nitriding or oxynitiriding so as to form acurrent confined layer including an insulating layer and a current pathwith a conductor passing a current through the insulating layer; andforming, on the current confined layer, a second magnetic layer.

Another aspect of the present invention relates to a method formanufacturing a magneto-resistance effect element, including: forming afirst magnetic layer; forming a first metallic layer, on the firstmagnetic layer, mainly containing an element selected from the groupconsisting of Cu, Au, Ag; forming a second metallic layer, on the firstmetallic layer, mainly containing Al; forming a functional layer, on thesecond metallic layer, mainly containing an element selected from thegroup consisting of Si, Hf, Ti, Mo, W, Nb, Mg, Cr and Zr; treating thesecond metallic layer and the functional layer by means of oxidizing,nitriding or oxynitiriding so as to form a current confined layerincluding an insulating layer and a current path with a conductorpassing a current through the insulating layer; and forming, on thecurrent confined layer, a second magnetic layer.

Still another aspect of the present invention relates to a method formanufacturing a magneto-resistance effect element, including: forming afirst magnetic layer; forming a first metallic layer, on the firstmagnetic layer, mainly containing an element selected from the groupconsisting of Cu, Au, Ag; forming a second metallic layer, on the firstmetallic layer, mainly containing Al; treating the second metallic layerby means of oxidizing, nitriding or oxynitiriding so as to form acurrent confined layer including an insulating layer and a current pathwith a conductor passing a current through the insulating layer; forminga functional layer, on the current confined layer, mainly containing anelement selected from the group consisting of Al, Si, Hf, Ti, Mo, W, Nb,Mg, Cr and Zr; and forming, on the functional layer, a second magneticlayer.

A further aspect of the present invention relates to a method formanufacturing a magneto-resistance effect element, including: forming afirst magnetic layer; forming a first metallic layer, on the firstmagnetic layer, mainly containing an element selected from the groupconsisting of Cu, Au, Ag; forming a first functional layer, on the firstmetallic layer, mainly containing an element selected from the groupconsisting of Si, Hf, Ti, Mo, W, Nb, Mg, Cr and Zr; forming a secondmetallic layer, on the first functional layer, mainly containing Al;forming a second functional layer, on the second metallic layer, mainlycontaining an element selected from the group consisting of Si, Hf, Ti,Mo, W, Nb, Mg, Cr and Zr; treating the second functional layer and thesecond metallic layer by means of oxidizing, nitriding or oxynitiridingso as to form a current confined layer including an insulating layer anda current path with a conductor passing a current through the insulatinglayer; and forming, on the current confined layer, a second magneticlayer.

A still further aspect of the present invention relates to a method formanufacturing a magneto-resistance effect element, including: forming afirst magnetic layer; forming a first metallic layer, on the firstmagnetic layer, mainly containing an element selected from the groupconsisting of Cu, Au, Ag; forming a first functional layer, on the firstmetallic layer, mainly containing an element selected from the groupconsisting of Si, Hf, Ti, Mo, W, Nb, Mg, Cr and Zr; forming a secondmetallic layer, on the first functional layer, mainly containing Al;treating the second metallic layer by means of oxidizing, nitriding oroxynitiriding so as to form a current confined layer including aninsulating layer and a current path with a conductor passing a currentthrough the insulating layer; forming a second functional layer, on saidcurrent confined layer, mainly containing an element selected from thegroup consisting of Al, Si, Hf, Ti, Mo, W, Nb, Mg, Cr and Zr; andforming, on the second functional layer, a second magnetic layer.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an embodiment of themagneto-resistance effect element according to the present invention.

FIG. 2 is a schematic view illustrating the area in the vicinity of thespacer layer of the magneto-resistance effect element in FIG. 1.

FIG. 3 is another schematic view illustrating the area in the vicinityof the spacer layer of the magneto-resistance effect element in FIG. 1.

FIG. 4 is still another schematic view illustrating the area in thevicinity of the spacer layer of the magneto-resistance effect element inFIG. 1.

FIG. 5 is a flowchart in a method for a magneto-resistance effectelement according to the present invention.

FIG. 6 is views relating to the formation process of a spacer layercontaining an adhesion developing layer.

FIG. 7 is other views relating to the formation process of a spacerlayer containing an adhesion developing layer.

FIG. 8 is also other views relating to the formation process of a spacerlayer containing an adhesion developing layer.

FIG. 9 is further other views relating to the formation process of aspacer layer containing an adhesion developing layer.

FIG. 10 is still further other views relating to the formation processof a spacer layer containing an adhesion developing layer.

FIG. 11 is a schematic view illustrating a film forming apparatus formanufacturing a magneto-resistance effect element according to thepresent invention.

FIG. 12 is a cross sectional view showing the state where themagneto-resistance effect element as described in an embodiment of thepresent invention is incorporated in a magnetic head.

FIG. 13 is another cross sectional view showing the state where themagneto-resistance effect element as described in an embodiment of thepresent invention is incorporated in a magnetic head.

FIG. 14 is a perspective view illustrating an essential part of amagnetic recording/reproducing device according to the presentinvention.

FIG. 15 is an enlarged perspective view illustrating the magnetic headassembly of the magnetic recording/reproducing device which is locatedforward from the actuator arm, as viewed from the side of the disk.

FIG. 16 is a view illustrating a magnetic memory matrix according to thepresent invention.

FIG. 17 is a view illustrating another magnetic memory matrix accordingto the present invention.

FIG. 18 is a cross sectional view illustrating an essential part of themagnetic memory.

FIG. 19 is a cross sectional view of the magnetic memory illustrated inFIG. 17, taken on line “A-A′”.

DETAILED DESCRIPTION OF THE INVENTION

The inventors had intensely studied to achieve the above object. As aresult, the inventors found out the following facts of the matter. Inthe CCP-CPP type magneto-resistance effect element, the reliability ofthe element depends particularly on the adhesion between the insulatinglayer (CCP-NOL) composing the spacer layer and the adjacent metalliclayer composing the same spacer layer or the adjacent magnetic layer. Inthis case, when a current is flowed in the stacking direction throughthe CCP-CPP type magneto-resistance effect element under operation, oneor more layers may be peeled off and the properties of one or morelayers may be deteriorated at the corresponding interface(s)therebetween in which the current density is increased, which affectsthe spin-dependent conduction and the reliability of the element to nosmall extent.

In this point of view, the inventors found out that if the functionallayer with large adhesion is formed at the one or more interfacesaffecting the deterioration in property of the layers composing theelement, the adhesion at the interface(s) can be enhanced so as todevelop the reliability of the element. According to the embodiment,therefore, the intended CCP-CPP type magneto-resistance effect elementwith high reliability can be provided.

The enhancement of the reliability of the element can contribute to theenhancement of the damage robustness and heat robustness of the elementunder various condition in addition to the manufacture of the HDD. As aresult, the magneto-resistance effect element can be applied for aserver and a head of enterprise requiring high reliability. The highreliability magnetic head with another feature except high densityrecording becomes important in technology advances of recent years asthe use application of HDD is increased. The long lifetime of magnetichead becomes very important in view of the enlargement of the useapplication of HDD. The high reliability magnetic head becomes veryeffective for an HDD in a car navigation system requiring a severethermal condition.

The high reliability magnetic head can be employed for an HDD in such ahousehold electronic appliance as a normal personal computer, a portablemusic player or a cellular phone in addition to the high-value addedHDD.

As described above, the functional layer with adhesion may be composedof a single layer or a plurality of layers which are separated from oneanother. The number of layer constituting the functional layer can bedetermined on the adhesion requiring for the corresponding interface(s).

The formation process of the functional layer is appropriatelycontrolled in accordance with the number of layer composing thefunctional layer to be formed at the corresponding interface(s).

In an embodiment, an additional metallic layer mainly containing anelement selected from the group consisting of Cu, Au, Ag may be formedon the current confined layer or on the functional layer. The additionalmetallic layer functions as a barrier layer to prevent the deteriorationof the second magnetic layer located above the spacer layer through theprevention of the diffusion of oxygen and nitrogen contained in theinsulating layer (CCP-NOL layer) of the spacer layer into the secondmagnetic layer, and as a seed layer to enhance the crystallinity of thesecond magnetic layer.

The thickness of the functional layer may be set within 0.1 to 0.5 nm.Then, the treatment through oxidizing, nitriding or oxynitiriding may beconducted under ion beam irradiation or plasma contact.

According to the aspects of the present invention can be provided amagneto-resistance effect element which can be applied for a magneticrecording device of high density recording and develop the reliabilityand the method for manufacturing the same magneto-resistance effectelement.

Hereinafter, the present invention will be described in detail withreference to the drawings.

(Magneto-Resistance Effect Element)

FIG. 1 is a perspective view illustrating a magneto-resistance effectelement (CCP-CPP type element) according to an embodiment of the presentinvention. Some or all components throughout the drawings in the presentapplication are schematically illustrated so that the illustratedthickness ratio for the components is different from the real thicknessratio for the components.

The magneto-resistance effect element illustrated in FIG. 1 includes amagneto-resistance effect element 10, a top electrode 11 and a bottomelectrode 20 which are disposed so as to sandwich the magneto-resistanceeffect element 10. Herein, the illustrated stacking structure is formedon a base (not shown).

The magneto-resistance effect element 10 includes an underlayer 12, apinning layer 13, a pinned layer 14, a bottom metallic layer 15, aCCP-NOL layer 16 (an insulating layer 161 and a current path 162), a topmetallic layer 17, a free layer 18 and a cap layer 19 which aresubsequently stacked and formed. Among them, the pinned layer 14, thebottom metallic layer 15, the CPP-NOL layer 16, the top metallic layer17 and the free layer 18 constitute a spin valve film which isconfigured such that the non-magnetic spacer layer is sandwiched betweenthe two ferromagnetic layers. The bottom metallic layer 15, the CCP-NOLlayer 16 and the top metallic layer 17 constitute the spacer layerentirely. For clarifying the structural feature of themagneto-resistance effect element, the extreme thin oxide layer 16 isrepresented under the condition that the thin oxide layer 16 isseparated from the upper and lower layers (the bottom metallic layer 15and the top metallic layer 17).

Then, the components of the magneto-resistance effect element will bedescribed. The bottom electrode 11 functions as an electrode for flowinga current in the direction perpendicular to the spin valve film. Inreal, the current can be flowed through the spin valve film in thedirection perpendicular to the film surface thereof by applying avoltage between the bottom electrode 11 and the top electrode 20. Thechange in resistance of the spin valve film originated from themagneto-resistance effect can be detected by utilizing the current. Inother words, the magnetization detection can be realized by the currentflow. The bottom electrode 11 is made of a metallic layer with arelatively small electric resistance for flowing the current to themagneto-resistance effect element sufficiently.

The underlayer 12 may be composed of a buffer layer 12 a and a seedlayer 12 b. The buffer layer 12 a can be employed for the compensationof the surface roughness of the bottom electrode 11. The seed layer 12 bcan be employed for controlling the crystalline orientation and thecrystal grain size of the spin valve film to be formed on the underlayer12.

The buffer layer 12 a may be made of Ta, Ti, W, Zr, Hf, Cr or an alloythereof. The thickness of the buffer layer 12 a is preferably set within2 to 10 nm, more preferably set within 3 to 5 nm. If the buffer layer 12a is formed too thin, the buffer layer 12 a can exhibit the inherentbuffering effect. If the buffer layer 12 a is formed too thick, theSeries resistance not contributing to the MR may be increased. If theseed layer 12 b can exhibit the buffering effect, the buffer layer 12 amay be omitted. In a preferable example, the buffer layer 12 a is madeof a Ta layer with a thickness of 3 nm.

The seed layer 12 b may be made of any material controllable for thecrystalline orientation of (a) layer(s) to be formed thereon. Forexample, the seed layer 12 b may be made preferably of a metallic layerwith a fcc-structure (face-centered cubic structure), a hcp-structure(hexagonal close-packed structure) or a bcc-structure (body-centeredcubic structure). Concretely, the seed layer 12 b may be made of Ru withhcp-structure or NiFe with fcc-structure so that the crystallineorientation of the spin valve film to be formed thereon can be renderedan fcc (111) faced orientation. In this case, the crystallineorientation of the pinning layer 13 (e.g., made of PtMn) can be renderedan fct-structure (face-centered tetragonal structure)-regulatedorientation or a bcc (110) faced orientation.

In order to exhibit the inherent seeding function of the seed layer 12 bof enhancing the crystalline orientation sufficiently, the thickness ofthe seed layer 12 b is set preferably within 1 to 5 nm, more preferablywithin 1.5 to 3 nm. In a preferable example, the seed layer 12 b may bemade of a Ru layer with a thickness of 2 nm.

The crystalline orientation for the spin valve film and the pinninglayer 13 can be measured by means of X-ray diffraction. For example, theFWHMs (full width at half maximum) in X-ray rocking curve of the fcc(111) peak of the spin valve film, the fct (111) peak or the bcc (110)peak of the pinning layer 13(PtMn) can be set within a range of 3.5 to 6degrees, respectively under good crystallinity. The dispersion of theorientation relating to the spin valve film and the pinning layer can berecognized by means of diffraction spot using cross section TEM.

The seed layer 12 b may be made of a NiFe-based alloy (e.g.,Ni_(x)Fe_(100-x): X=90 to 50%, preferably 75 to 85%) layer of aNiFe-based non-magnetic ((Ni_(x)Fe_(100-x))_(100-y)X_(y): X═Cr, V, Nb,Hf, Zr, Mo)) layer. In the latter case, the addition of the thirdelement “X” renders the seed layer 12 b non-magnetic. The crystallineorientation of the seed layer 12 b of the NiFe-based alloy can beenhanced easily so that the FWHM in X-ray rocking curve can be renderedwithin a range of 3 to 5 degrees.

The seed layer 12 b functions not only as the enhancement of thecrystalline orientation, but also as the control of the crystal grainsize of the spin valve film. Concretely, the crystal grain size of thespin valve film can be controlled within a range of 5 to 40 nm so thatthe fluctuation in performance of the magneto-resistance effect elementcan be prevented, and thus, the higher MR ratio can be realized eventhough the magneto-resistance effect element is downsized.

The crystal grain size of the spin valve film can be determined on thecrystal grain size of the layer formed on the seed layer 12 b by meansof cross section TEM. In the case of a bottom type spin valve film wherethe pinning layer 14 is located below the spacer layer 16, the crystalgrain size of the spin valve film can be determined on the crystal grainsize of the pinning layer 13 (antiferromagnetic layer) or the pinnedlayer 14 (fixed magnetization layer) to be formed on the seed layer 12b.

With a reproducing head in view of high recording density, the elementsize is set to 100 nm or below, for example. Therefore, if the crystalgrain size is set larger for the element size, the elementcharacteristics may be fluctuated. In this point of view, it is notdesired that the crystal grain size of the spin valve film is set largerthan 40 nm. Concretely, the crystal grain size of the spin valve film isset preferably within 5 to 40 nm, more preferably within 5 to 20 nm.

Too large crystal grain size may cause the decrease of the number ofcrystal grain per element surface so as to cause fluctuation incharacteristics of the reproducing head. With the CCP-CPP elementforming a current path, it is not desired to increase the crystal grainsize than a prescribed grain size. In contrast, too small crystal grainsize may deteriorate the crystalline orientation. In this point of view,it is required that the crystal grain size is determined in view of theupper limited value and the lower limited value, e.g., within a range of5 to 20 nm.

With the use of MRAM, however, the element size may be increased to 100nm or over so that the crystal grain size can be increased to about 40nm without the above-mentioned problem. Namely, if the seed layer 12 bis employed, the crystal grain size may be increased than the prescribedgrain size.

In order to set the crystal grain size within 5 to 20 nm, the seed layer12 b may be made of a Ru layer with a thickness of 2 nm or a NiFe-basednon-magnetic ((Ni_(x)Fe_(100-x))_(100-y)X_(y): X═Cr, V, Nb, Hf, Zr, Mo,preferably y=0 to 30%)) layer.

In contrast, in the case that the crystal grain size is increased morethan 40 nm and thus, is rendered coarse, the content of the thirdadditive element is preferably increased more than the value describedabove. For example, with NiFeCr alloy, the content of Cr is preferablyset within 35 to 45% so as to set the composition of the NiFeCr alloy tothe composition exhibiting intermediate phase structure between thefcc-structure and the bcc-structure. In this case, the resultant NiFeCrlayer can have the bcc-structure.

As descried above, the thickness of the seed layer 12 b is setpreferably within 1 to 5 nm, more preferably within 1.5 to 3 nm. Toothin seed layer 12 b may deteriorate the crystalline orientationcontrollability. In contrast, too thick seed layer 12 b may increase theSeries resistance of the element and rough the interface for the spinvalve film.

The pinning layer 13 functions as applying the unidirectional anisotropyto the ferromagnetic layer to be the pinned layer 14 on the pinninglayer 13 and fixing the magnetization of the pinned layer 14. Thepinning layer 13 may be made of an antiferromagnetic material such asPtMn, PdPtMn, IrMn, RuRhMn, FeMn, NiMn. In view of the use of theelement as a high density recording head, the pinning layer 13 ispreferably made of IrMn because the IrMn layer can apply theunidirectional anisotropy to the pinned layer 14 in comparison with thePtMn layer even though the thickness of the IrMn layer is smaller thanthe thickness of the PtMn layer. In this point of view, the use of theIrMn layer can reduce the gap width of the intended element for highdensity recording.

In order to apply the unidirectional anisotropy with sufficientintensity, the thickness of the pining layer 13 is appropriatelycontrolled. In the case that the pinning layer 13 is made of PtMn orPdPtMn, the thickness of the pinning layer 13 is set preferably within 8to 20 nm, more preferably within 10 to 15 nm. In the case that thepinning layer 13 is made of IrMn, the unidirectional anisotropy can beapplied even though the thickness of the pinning layer 13 of IrMn is setsmaller than the thickness of the pinning layer 13 of PtMn. In thispoint of view, the thickness of the pinning layer 13 of IrMn is setpreferably within 4 to 18 nm, more preferably within 5 to 15=m. In apreferred embodiment, the thickness of the IrMn pinning layer 13 is setto 10 nm.

The pinning layer 13 may be made of a hard magnetic layer instead of theantiferromagnetic layer. For example, the pinning layer 13 may be madeof CoPt (Co=50 to 85%), (CoPt_(100-x))_(100-y)Cr_(y): X=50 to 85%, Y=0to 40%) or FePt (Pt=40 to 60%). Since the hard magnetic layer has asmaller specific resistance, the Series resistance and the AreaResistance RA of the element can be reduced.

In a preferred embodiment, the pinned layer (fixed magnetization layer)14 is formed as a synthetic pinned layer composed of the bottom pinnedlayer 141 (e.g., Co₉₀Fe₁₀ 3.5 nm), the magnetic coupling layer 142(e.g., Ru) and the top pinned layer 143 (e.g., Fe₅₀Co₅₀ 1 nm/Cu 0.25nm×2/Fe₅₀Co₅₀ 1 nm). The pinning layer 13 (e.g., IrMn layer) is coupledvia magnetic exchange with the bottom pinned layer 141 formed on thepinning layer 13 so as to apply the unidirectional anisotropy to thebottom pinned layer 141. The bottom pinned layer 141 and the top pinnedlayer 143 which are located under and above the magnetic coupling layer142, respectively, are strongly magnetically coupled with one another sothat the direction of magnetization in the bottom pinned layer 141becomes anti-paralleled to the direction of magnetization in the toppinned layer 143.

The bottom pinned layer 141 may be made of Co_(x)Fe_(100-x) alloy (X=0to 100), Ni_(x)Fe_(100-x) (X=0 to 100) or an alloy thereof containing anon magnetic element. The bottom pinned layer 141 may be also made of asingle element such as Co, Fe, Ni or an alloy thereof. It is desiredthat the magnetic thickness (saturated magnetization Bs×thickness t(Bst)) of the bottom pinned layer 141 is set almost equal to the one ofthe top pinned layer 143. Namely, it is desired that the magneticthickness of the top pinned layer 143 corresponds to the magneticthickness of the bottompinned layer 141. For example, when the toppinned layer 143 of Fe₅₀Co₅₀ 1 nm/Cu 0.25 nm×2/Fe₅₀Co₅₀ 1 nm isemployed, the magnetic thickness of the top pinned layer 143 is set to2.2 T×3 nm=6.6 T nm because the saturated magnetization of the toppinned layer 143 is about 2.2 T. When the bottom pinned layer 141 ofCo₉₀Fe₁₀ is employed, the thickness of the bottom pinned layer 141 isset to 6.6 T nm/1.8 T=3.66 nm for the magnetic thickness of 6.6 T nmbecause the saturated magnetization of Co₉₀Fe₁₀ is about 1.8 T. In thispoint of view, it is desired that the thickness of the bottom pinnedlayer 141 made of Co₉₀Fe₁₀ is set to about 3.6 nm. The thickness of thebottom pinned layer 141 is preferably set within 2 to 5 nm in view ofthe magnetic strength of the unidirectional anisotropy relating to thepinning layer 13 (e.g., IrMn layer) and the magnetic strength of theantiferromagnetic coupling between the bottom pinned layer 141 and thetop pinned layer 143 via the magnetic coupling layer 142 (e.g., Rulayer). Too thin bottom pinned layer 141 causes the decrease of the MRratio. In contrast, too thick bottom pinned layer 141 causes thedifficulty of obtaining the unidirectional anisotropy magnetic fieldrequiring for the operation of the element. In a preferred embodiment,the bottom pinned layer 141 may be made of a Co₉₀Fe₁₀ layer with athickness of 3.4 nm.

The magnetic coupling layer 142 (e.g., Ru layer) causes theantiferromatic coupling between the bottom pinned layer 141 and the toppinned layer 143 which are located under and above the magnetic couplinglayer 142. In the case that the magnetic coupling layer 142 is made ofthe Ru layer, the thickness of the Ru layer is preferably set within 0.8to 1 nm. Only if the antiferromagnetic coupling between the pinnedlayers located under and above the magnetic coupling layer 142 can begenerated, the magnetic coupling layer 142 may be made of anothermaterial except Ru or the thickness of the magnetic coupling layer 142may be varied within 0.3 to 0.6 nm instead of the thickness range of0.8-1 nm. The former thickness range of 0.3 to 0.6 nm corresponds to thefirst peak of RKKY (Runderman-Kittel-Kasuya-Yoshida), and the latterthickness range of 0.8 to 1 nm corresponds to the second peak of RKKY.With the thickness range of the first peak of RKKY, the magneticcoupling layer 142 can exhibit an extremely large antiferromagneticfixing strength, but the allowable thickness range of the magneticcoupling layer 142 is reduced. In a preferred embodiment, the magneticcoupling layer 142 may be made of the Ru layer with a thickness of 0.9nm so as to realize the antiferromagnetic coupling for the pinned layersstably.

The top pinned layer 143 may be made of Fe₅₀Co₅₀ 1 nm/Cu 0.25nm×2/Fe₅₀Co₅₀ 1 nm. The top pinned layer 143 composes the spin dependentscattering unit. The top pinned layer 143 can contribute directly to theMR effect, and thus, the material and thickness of the top pinned layer143 are important so as to realize a large MR ratio. The magneticmaterial of the top pinned layer 143 to be positioned at the interfacefor the CCP-NOL layer 16 is important in view of the contribution of thespin dependent interface scattering.

Then, the effect/function of the top pinned layer 143 of the Fe₅₀Co₅₀layer with bcc-structure will be described. In this case, since the spindependent interface scattering is enhanced, the MR ratio can beenhanced. As the FeCo-based alloy with bcc-structure, a Co_(x)Fe_(100-x)alloy (X=30 to 100) or a similar CoFe-based alloy containing an additiveelement can be exemplified. Among them, a Fe₄₀Co₆₀ alloy through aFe₆₀Co₄₀ alloy may be employed in view of the above-describedrequirements.

In the case that the top pinned layer 143 is made of the magnetic layerwith bcc-structure easily exhibiting the large MR ratio, the thicknessof the top pinned layer 143 is preferably set to 1.5 nm or over so as tomaintain the bcc-structure thereof stably. Since the spin valve film ismade mainly of a metallic material with fcc-structure or fct-structure,only the top pinned layer 143 may have the bcc-structure. In this pointof view, too thin top pinned layer 143 can not maintain thebcc-structure thereof stably so as not to obtain the large MR ratio.

Herein, the top pinned layer 143 is made of the Fe₅₀Co₅₀ layers and theextremely thin Cu layers. The total thickness of the Fe₅₀Co₅₀ layers is3 nm and each Cu layer is formed on the corresponding Fe₅₀Co₅₀ layerwith a thickness of 1 nm. The thickness of the Cu layer is 0.25 nm andthe total thickness of the top pinned layer 143 is 3.5 nm.

It is desired that the thickness of the top pinned layer 143 is set to 5nm or below so as to generate a large pinning (fixing) magnetic field.In view of the large pinning (fixing) magnetic field and the stabilityof the bcc-structure in the top pinned layer 143, the thickness of thetop pinned layer 143 is preferably set within 2 to 4 nm.

The top pinned layer 143 may be made of a Co₉₀Fe₁₀ alloy withfcc-structure or a Co alloy with hcp-structure which used to be widelyemployed for a conventional magneto-resistance effect element, insteadof the magnetic material with the bcc-structure. The top pinned layer143 can be made of a single element such as Co, Fe, Ni or an alloycontaining at least one of Co, Fe, Ni. In view of the large MR ratio ofthe top pinned layer 143, the FeCo alloy with the bcc-structure, the Coalloy containing Co element of 50% or over and the Ni alloy containingNi element of 50% or over are in turn preferable.

In this embodiment, the top pinned layer 143 is made of the magneticlayers (FeCo layers) and the non magnetic layers (extremely thin Culayers). In this case, the top pinned layer 143 can enhance the spindependent scattering effect which is also called as a “spin dependentbulk scattering effect”, originated from the extremely thin Cu layers.

The spin dependent bulk scattering effect is utilized in pairs for thespin dependent interface scattering effect. The spin dependent bulkscattering effect means the occurrence of an MR effect in a magneticlayer and the spin dependent interface scattering effect means theoccurrence of an MR effect at an interface between a spacer layer and amagnetic layer.

Hereinafter, the enhancement of the bulk scattering effect of thestacking structure of the magnetic layer and the non magnetic layer willbe described. With the CCP-CPP element, since a current is confined inthe vicinity of the CCP-NOL layer 16, the resistance in the vicinity ofthe CCP-NOL layer 16 contributes the total resistance of themagneto-resistance effect element. Namely, the resistance at theinterface between the CCP-NOL layer 16 and the magnetic layers (pinnedlayer 14 and the free layer 18) contributes largely to themagneto-resistance effect element. That means the contribution of thespin dependent interface scattering effect becomes large and importantin the CCP-CPP element. The selection of magnetic material located atthe interface for the CCP-NOL layer 16 is important in comparison with aconventional CPP element. In this point of view, the pinned layer 143 ismade of the FeCo alloy with the bcc-structure exhibiting the large spindependent interface scattering effect as described above.

However, it may be that the spin dependent bulk scattering effect shouldbe considered so as to develop the MR ratio. In view of the developmentof the spin dependent bulk scattering effect, the thickness of the thinCu layer is set preferably within 0.1 to 1 nm, more preferably within0.2 to 0.5 nm. Too thin Cu layer can not develop the spin dependent bulkscattering effect sufficiently. Too thick Cu layer may reduce the spindependent bulk scattering effect and weaken the magnetic couplingbetween the magnetic layers via the nonmagnetic Cu layer, which themagnetic layers sandwiches the non magnetic Cu layer, therebydeteriorating the property of the pinned layer 14. In a preferredembodiment, in this point of view, the thickness of the non-magnetic Culayer is set to 0.25 nm. The non-magnetic layer sandwiched by themagnetic layers may be made of Hf, Zr, Ti instead of Cu. In the casethat the pinned layer 14 contains the non-magnetic layer(s), thethickness of the one magnetic layer such as a FeCo layer which isseparated by the non-magnetic layer is set preferably within 0.5 to 2nm, more preferably within 1 to 1.5 nm.

In the above embodiment, the top pinned layer 143 is constituted of thealternately stacking structure of FeCo layer and Cu layer, but may bemade of an alloyed layer of FeCo and Cu. The composition of theresultant FeCoCu alloy may be set to ((Fe_(x)Co_(100-x))_(100-y)Cu_(y):x=30 to 100% Cr, Y=3 to 15%), but set to another composition range. Thethird element to be added to the main composition of FeCo may beselected from Hf, Zr, Ti instead of Cu.

The top pinned layer 143 may be also made of a single element such asCo, Fe, Ni or an alloy thereof. In a simplified embodiment, the toppinned layer 143 may be made of an Fe₉₀Co₁₀ layer with a thickness of 2to 4 nm, as occasion demands, containing a third additive element.

Then, the spacer layer will be concretely described. The bottom metalliclayer 15 is employed for the formation of the current path 162 and thus,functions as a supplier for the current path 162. It is not requiredthat the metallic layer 15 remains as it is apparently after theformation of the current path 162. In this point of view, the bottommetallic layer 15 functions broadly as a part of the spacer layer. Thebottom metallic layer 15 functions as a stopper layer preventing theoxidization of the magnetic layer 143 which is located below the CCP-NOLlayer 16 in the formation of the CCP-NOL layer 16.

The CCP-NOL layer 16 includes the insulating layer 161 and the currentpath 162. The insulating layer 161 is made of oxide, nitride, oxynitrideor the like. For example, the insulating layer 161 may be made of anAl₂O₃ amorphous structure or an MgO crystalline structure. In order toexhibit the inherent function of the spacer layer, the thickness of theinsulating layer 161 is set preferably within 1 to 3 nm, more preferablywithin 1.5 to 2.5 nm. The CCP-NOL layer 16 functions as a currentconfined layer.

The insulating layer 161 may be made of a typical insulating materialsuch as Al₂O₃-based material, as occasion demands, containing a thirdadditive element such as Ti, Hf, Mg, Zr, V, Mo, Si, Cr, Nb, Ta, W, B, C,V. The content of the additive element may be appropriately controlledwithin 0 to 50%. In a preferred embodiment, the insulating layer 161 ismade of an Al₂O₃ layer with a thickness of about 2 nm.

The insulating layer 161 may be made of Ti oxide, Hf oxide, Mg oxide, Zroxide, Cr oxide, Ta oxide, Nb oxide, Mo oxide, Si oxide or V oxideinstead of the Al oxide such as the Al₂O₃. In the use of another oxideexcept the Al oxide, a third additive element such as Ti, Hf, Mg, Zr, V,Mo, Si, Cr, Nb, Ta, W, B, C, V may be added to the oxide as occasiondemands. The content of the additive element may be appropriatelycontrolled within 0 to 50%.

The insulating layer 161 may be also made of a nitride or an oxynitridecontaining, as a base material, Al, Si, Hf, Ti, Mg, Zr, V, Mo, Nb, Ta,W, B, C only if the insulating layer 161 can exhibit the inherentinsulating function.

The current path 162 functions as a path to flow a current in thedirection perpendicular to the film surface of the CCP-NOL layer 16 andthen, confining the current. The current path 162 also functions as aconductor to flow the current in the direction perpendicular to the filmsurface of the insulating layer 161 and is made of a metal such as Cu.In other words, the spacer layer 16 exhibits the current-confined pathstructure (CCP structure) so as to enhance the MR ratio from the currentconfining effect.

The current path 162 (CCP) may be made of Au, Ag, Ni, Co, Fe or an alloycontaining at least one from the listed elements instead of Cu. In apreferred embodiment, the current path 162 is made of a Cu alloy. Thecurrent path 162 may be made of an alloy layer of CuNi, CuCo or CuFe.Herein, the content of Cu in the alloy is set preferably to 50% or overin view of the enhancement of the MR ratio and the reduction of theinterlayer coupling field, Hin between the pinned layer 14 and the freelayer 18.

The content in oxygen and nitrogen of the current path 162 is muchsmaller than (at least half as large as) the one of the insulating layer161. The current path 162 is generally crystallized. Since theresistance of the crystalline phase is smaller than the resistance ofthe non-crystalline phase, the current path 162 can easily conduct theinherent function.

The top metallic layer 17 functions as a barrier layer protecting theoxidization of the free layer 18 to be formed thereon through thecontact with the oxide of the CCP-NOL layer 16 so that the crystalquality of the free layer 18 cannot be deteriorated. For example, whenthe insulating layer 161 is made of an amorphous material (e.g., Al₂O₃),the crystal quality of a metallic layer to be formed on the layer 161may be deteriorated, but when a layer (e.g., Cu layer) to develop thecrystal quality of fcc-structure is provided (under the condition thatthe thickness of the metallic layer is set to 1 nm or below), thecrystal quality of the free layer 18 can be remarkably improved.

It is not always required to provide the top metallic layer 17 dependenton the kind of material in the CCP-NOL layer 16 and/or the free layer18. Moreover, if the annealing condition is optimized and theappropriate selection of the materials of the insulating layer 161 ofthe thin oxide layer 16 and the free layer 18 is performed, thedeterioration of the crystal quality of the free layer 18 can beprevented, thereby omitting the metallic layer 17 of the CCP-NOL layer16.

In view of the manufacturing yield of the magneto-resistance effectelement, it is desired to form the top metallic layer 17 on the CCP-NOLlayer 16. In a preferred embodiment, the top metallic layer 17 can bemade of a Cu layer with a thickness of 0.5 nm.

The top metallic layer 17 may be made of Au or Ag instead of Cu.Moreover, it is desired that the top metallic layer 17 is made of thesame material as the material of the current path 162 of the CCP-NOLlayer 16. If the top metallic layer 17 is made of a material differentfrom the material of the current path 162, the interface resistancebetween the layer 17 and the path 162 is increased, but if the topmetallic layer 17 is made of the same material as the material of thecurrent path 162, the interface resistance between the layer 17 and thepath 162 is not increased.

The thickness of the top metallic layer 17 is set preferably within 0 to1 nm, more preferably within 0.1 to 0.5 nm. Too thick top metallic layer17 may extend the current confined through the spacer layer 16 thereat,resulting in the decrease of the MR ratio due to the insufficientcurrent confinement.

The essential point in this embodiment is directed at the remarkableimprovement in reliability of the element by forming an adhesiveenhancing portion in at least a portion of the spacer layer. Details forthe adhesive enhancing portion will be described hereinafter.

The free layer 18 is a ferromagnetic layer of which the direction ofmagnetization is varied commensurate with the external magnetic field.For example, the free layer 18 is made of a double-layered structure ofCo₉₀Fe₁₀ 1 nm/Ni₈₃Fe₁₇ 3.5 nm. In this case, the Co₉₀Fe₁₀ layer isformed at the interface between the free layer 18 and the spacer layer16, which is desirable in the case that the Ni₈₃Fe₁₇ layer is formed atthe interface therebetween. In order to realize the large MR ratio, theselection of magnetic material of the free layer 18 in the vicinity ofthe spacer 16, that is, at the interface therebetween is important. Thefree layer 18 may be made of a single Co₉₀Fe₁₀ layer with a thickness of4 nm without a NiFe layer or a triple-layered structure ofCoFe/NiFe/CoFe.

Among CoFe alloys, the Co₉₀Fe₁₀ layer is preferably employed in view ofthe stable soft magnetic property. If a CoFe alloy similar to theCo₉₀Fe₁₀ alloy in composition is employed, it is desired that thethickness of the resultant CoFe alloy layer is set within 0.5 to 4 nm.Moreover, the free layer 18 may be made of Co_(x)Fe_(100-x) (X=70 to90%).

Then, the free layer 18 is made of an alternately stacking structure ofCoFe layers or Fe layers with a thickness of 1 to 2 nm and extremelythin Cu layers with a thickness of 0.1 to 0.8 nm.

In the case that the CCP-NOL layer 16 is made of the Cu layer, it isdesired that the FeCo layer with bcc-structure is employed as theinterface material thereof for the spacer layer 16 so as to enhance theMR ratio in the same manner as the pinned layer 14. As the FeCo layerwith bcc-structure, the Fe_(x)Co_(100-x) (X=30 to 100) or, as occasiondemands, containing a third additive element, may be employed. In apreferred embodiment, a Co₉₀Fe₁₀ 1 nm/Ni₈₃Fe₁₇ 3.5 nm may be employed.Instead of the FeCo layer with bcc-structure, a CoFe layer withfcc-structure may be employed.

The cap layer 19 functions as protecting the spin valve film. The caplayer 19 may be made of a plurality of metallic layers, e.g., adouble-layered structure of Cu 1 nm/Ru 10 nm. The layered turn of the Culayer and the Ru layer may be switched so that the Ru layer is locatedin the side of the free layer 18. In this case, the thickness of the Rulayer is set within 0.5 to 2 nm. The exemplified structure isparticularly desired for the free layer 19 of NiFe because themagnetostriction of the interface mixing layer formed between the freelayer 18 and the cap layer 19 can be lowered due to the non-solutionbetween Ru and Ni.

When the cap layer 19 is made of the Cu/Ru structure or the Ru/Custructure, the thickness of the Cu layer is set within 0.5 to 10 nm andthe thickness of the Ru layer is set smaller, e.g., within 0.5 to 5 nmdue to the large specific resistance.

The cap layer 19 may be made of another metallic layer instead of the Culayer and/or the Ru layer. The structure of the cap layer 19 is notlimited only if the cap layer 19 can protect the spin valve film. If theprotective function of the cap layer 19 can be exhibited, the cap layer19 may be made of still another metal. Attention should be paid to themetallic layer because the kind of material of the cap layer may changethe MR ratio and the long reliability. In view of the stable MR ratioand long reliability, the Cu layer and/or the Ru layer is preferable forthe cap layer.

The top electrode 20 functions as flowing a current through the spinvalve film in the direction perpendicular to the film surface of thespin valve film. The intended current can be flowed through the spinvalve film in the direction perpendicular to the film surface byapplying a voltage between the top electrode 20 and the bottom electrode11. The top electrode 20 may be made of a material with smallerresistance (e.g., Cu or Au).

FIGS. 2 to 4 are enlarged schematic views, each illustrating the area inthe vicinity of the spacer layer of the magneto-resistance effectelement in this embodiment. FIG. 2 relates to an embodiment where theadhesion enhancing layer 21L is formed at the interface between thebottom surface of the insulating layer 161 and bottom metallic layer 15and at the interface between insulating layer 161 and the current path162. FIG. 3 relates to an embodiment where the adhesion enhancing layer21U is formed at the interface between the top surface of the insulatinglayer 161 and the top metallic layer 17. FIG. 4 relates to an embodimentwhere the adhesion enhancing layer 21L is formed at the interfacebetween the bottom surface of the insulating layer 161 and bottommetallic layer 15 and at the interface between insulating layer 161 andthe current path 162 and the adhesion enhancing layer 21U is formed atthe interface between the top surface of the insulating layer 161 andthe top metallic layer 17.

In the magneto-resistance effect element of this embodiment, since theadhesion enhancing layer(s) is (are) provided adjacent to the insulatinglayer 161, the adhesion between the insulating layer 161 and the currentpath 162, the bottom metallic layer 15, the adhesion between theinsulating layer 161 and the top metallic layer 17 or the adhesionbetween the insulating layer 161 and the current path 162, the bottommetallic layer 15 and the top metallic layer 17 can be enhanced. In thiscase, the adhesion between the interfaces of the layers as describedabove can be enhanced so that the characteristics and reliability of themagneto-resistance effect element can be enhanced. As a result, theadvanced in reliability CCP-CPP type magneto-resistance effect elementcan be provided.

As described above, since the insulating layer 161 mainly contains Al,Si, Hf, Ti, V, Ta, W, Mg, Cr or Zr, the adhesion enhancing layer 21L maybe also made of Al, Si, Hf, Ti, V, Ta, W, Mg, Cr or Zr. Otherwise, theadhesion enhancing layer 21L may contain an element with an oxideformation energy higher than the oxide formation energy of the elementcomposing the insulating layer 161 and lower than the oxide formationenergies of the elements composing the metallic layers 15, 17 and thecurrent path 162.

Table 1 lists the oxide formation energies of the corresponding elementsas described above. Referring to Table 1, when the insulating layer 161contains Al, the adhesion enhancing layer 21L may contain Si, Hf, Ti, V,W, Mg, Mo, Cr or Zr. When the insulating layer 161 contains Si, theadhesion enhancing layer 21L may contain Mo, V, W, Mg.

Herein, in the case that the matrix layer of the adhesion enhancinglayer is formed after the CCP-NOL layer 16 is formed, and the adhesionenhancing layer is formed at the interface between the insulating layer161 and the metallic layer 17 from the matrix layer, for example, theadhesion enhancing layer may contain the same element as the elementcomposing the insulating layer 161. The reason is that the oxygen of theinsulating layer becomes energetically stable so that the amount ofoxygen to be contacted with the metallic layer 17 can be lowered becausethe CCP-NOL layer is formed in advance.

TABLE 1 Oxide formation energy Element Oxide {×10⁻⁶ J/kmol} Main elementcomposing Au Au₂O₃ 163 metallic layer 15, current Ag Ag₂O −11 confiningCu CuO −127 path 162, and metallic layer 17 Main element composing CoCoO −213 pinned layer 14 and free Ni NiO −216 layer 18 Fe FeO −244 Mainelement to be Mo MoO₂ −502 incorporated in insulating Mg MgO −573 layer161, and adhesion V VO₂ −680 enhancing layers 21U and W WO₃ −763 21L SiSiO₂ −805 Ti TiO₂ −880 Zr TrO₂ 1037 Cr Cr₂O₃ −1048 Hf HfO₂ −1084 AlAl₂O₃ −1580 Ta Ta₂O₅ −1970

It is desired that the thickness of the adhesion enhancing layer is setlarger in view of the enhancement of adhesion thereof. However, if theadhesion enhancing layer is formed too thick, the current confinedthrough the CCP-NOL layer may extend at the pinned layer 14 and the freelayer 18, thereby reducing the enhancement effect of the spin dependentinterface scattering because the distance between the CCP-NOL layer 16and the pinned layer 14 and/or the distance between the CCP-NOL layer 16and the free layer 18 is elongated. Therefore, the thickness of theadhesion enhancing layer is set preferably within 0.05 to 1 nm, morepreferably within 0.1 to 0.5 nm.

The structure of the CCP-NOL layer 16 containing the adhesion enhancinglayer can be observed by means of the Local Electrode Atom Probe made by“Imago Scientific Instruments Inc”.

According to the three-dimensional atom probe, the composition of thematerial to be observed can be mapped three-dimensionally in the orderof atomic level. Concretely, the sample to be measured is processed inneedle shape so that the curvature radius of the forefront of the sampleis set within 30 to 100 nm and the length (height) of the sample is setto about 100 μm. Then, a high voltage is applied to the sample so as toevaporate the atoms from the forefront of the sample by means of theelectric field generated by the application of the high pulsed voltage,which the evaporated atoms are detected by the two-dimensional detector.The intended three-dimensional (x, y, z) structure can be obtained fromthe information in the depth (z-axis) direction by following the changesin position information of the atoms in the two dimensional (x, y) planewith time, which the position information of the atoms are detected bythe two-dimensional detector.

A three-dimensional atom probe made by “Oxford Instruments Inc.” orCameca Inc. may be employed instead of the three-dimensional atomicforce microprobe.

The electric field evaporation may be conducted by the application of alaser pulse instead of the pulsed voltage. In both cases, a biasingelectric field is applied by means of DC voltage. With the pulsedvoltage, the electric field requiring the electric field evaporation canbe generated in dependent on the amplitude of the voltage. With thelaser pulse, the sample is locally heated by the irradiation of thelaser pulse so that the electric field evaporation can be likely to begenerated.

The reason the structure of the CCP-NOL layer 16 can exhibit the highreliability will be described hereinafter.

A. Oxidization of Metal Adjacent to Insulating Layer 161 of CCP-NOLLayer 16

In the case that the insulating layer 161 of the CCP-NOL layer 16 ismade of Al₂O₃ and the metallic layers 15, 17 are made of Cu, the areasof the metallic layers 15, 17 contacting with the insulating layer 161are oxidized to form CuOx compounds. It is known that the CuOx compoundlowers the adhesion for the adjacent layer. In this way, an oxide of Cu,Au or Ag with a larger oxide formation energy is likely to lower theadhesion for the adjacent layer.

In the CCP-CPP element, when the adhesion of the metallic layer adjacentto the insulating layer 161 is lowered, the microscopic disorder of atomand the small film peeling may occur by the driving force originatedfrom the heat generation from the current flow. When a current is flowedin the CCP-CPP element, the current is concentrated in the vicinity ofthe metallic path. Therefore, since the current density around themetallic path is increased so as to generate the Joule heat, the areaaround the metallic path is locally heated. Then, the conductionelectrons attack the insulating layer in the vicinity of the currentpath, and thus, damage the insulating layer. In this way, the CCP-NOLlayer 16 is disposed under the severe condition due to the currentconcentration, which is different from a TMR (Tunneling MagnetoResistance) film.

When the magneto-resistance effect element is observed by means of crosssection TEM after the operation of current flowing, the interfacebetween the insulating layer and the adjacent metallic layer is notbroken, so it is considered that the microscopic disorder of atomaffects the spin dependent conduction.

In this way, when the adhesion of the metallic layer adjacent to theCCP-NOL layer 16 is lowered, the microscopic disorder of atom and thesmall film peeling may occur, thereby deteriorating the reliability ofthe intended magneto-resistance effect element. By providing theadhesion enhancing layer 21L as shown in FIGS. 2 ands 4, however, themicroscopic disorder of atom and the small film peeling can beprevented, thereby enhancing the reliability of the CCP-NOL layer 16 andthe reliability of the CCP-CPP type magneto-resistance effect elementcontaining the CCP-NOL layer. The principle relating the reliabilityenhancement will be described hereinafter.

B. Enhancement of Magneto-Resistance Effect Element Using AdhesionEnhancing Layer

The affection of the adhesion enhancing layer to the magneto-resistanceeffect element will be described referring to the embodiment relating toFIG. 2 where the adhesion enhancing layer 21L is formed between themetallic layer 15, the current path 162 and the insulating layer 161.

In the case that the adhesion enhancing layer is not provided, since theinsulating layer 161 containing much amount of oxygen is directlycontacted with the metallic layer 15 and the current path 162, themetallic portions of the metallic layer 15 and the current path 162 maybe oxidized.

In contrast, in the case that the adhesion enhancing layer is providedas shown in FIG. 2, the adhesion enhancing layer 21L is configured tocontain a kind of element with an oxide formation energy lower than theoxide formation energies of the elements composing the metallic layer 15and the current path 162 and higher than the oxide formation energy ofthe main element composing the insulating layer 161. Referring to theoxygen distribution relating to the insulating layer 161 and theadhesion enhancing layer 21L, since the oxide formation energy of theinsulating layer 161 is lower than the one of the adhesion enhancinglayer 21L so that the insulating layer 161 is likely to be oxidized incomparison with the adhesion enhancing layer 21L, the insulating layer161 contains much amount of oxygen. As a result, since the metalliclayer 15 and the current path 162 are contacted with the adhesionenhancing layer 21L containing less amount of oxygen, the oxidization ofthe metallic layer 15 and the current path 162 can be prevented.

The principle of the adhesion enhancement was not only describedreferring to the embodiment where the adhesion enhancing layer 21L isformed between the metallic layer 15, the current path 162 and theinsulating layer 161, but can be also described referring to anotherembodiment where the adhesion enhancing layer 21U is provided betweenthe insulating layer 161 and the top metallic layer 17. In this way, thereliability of the CCP-NOL layer 16 can be enhanced, and thus, thereliability of the magneto-resistance effect element can be alsoenhanced.

(Method for Manufacturing a Magneto-Resistance Effect Element)

Then, the method for manufacturing the magneto-resistance effect elementwill be described. FIG. 5 is a flow chart in a method for amagneto-resistance effect element according to the first embodiment.

As shown in FIG. 5, the underlayer 12 through the cap layer 19 aresubsequently formed schematically in accordance with the materialcompositions and the sizes (thickenesses) as described above StepsS11-S17). In this case, when the spacer layer composed of the metalliclayer 15, the CCP-NOL layer 16 and the metallic layer 17 is formed inStep S14, the adhesion enhancing layer 21L is formed at the interfacebetween the insulating layer 161 and the metallic layer 15, the currentpath 162, the metallic layer 17.

Hereinafter, the detail steps in Step S14 for the formation of theadhesion enhancing layer will be described. In this embodiment, supposethat the insulating layer 161 is made of an amorphous Al₂O₃ and thecurrent path 162 is made of a crystalline Cu.

FIG. 6 relates to the detail steps for the formation of the adhesionenhancing layer 21L as shown in FIG. 2.

First of all, the bottom metallic layer 15 is formed of Cu (S14-a1).Then, the metallic layer 21LM composing the matrix of the adhesionenhancing layer is formed (S14-a2). The metallic layer 21LM may be madeof a material (element) with an oxide formation energy higher than theoxide formation energy of the element mainly composing the CCP-NOL layerand lower than the oxide formation energy of the element composing themetallic layer 15. In this embodiment, since the insulating layer 161 ismade of Al₂O₃, the adhesion enhancing layer 21L (metallic layer 21LM)may be made of Si, Hf, Ti, V, W, Mg, MO, Cr or Zr referring to Table 1.

Then, the layer 161M composing the matrix of the CCP-NOL layer is formed(S14-a3). In this embodiment, since the insulating layer 161 is made ofAl₂O₃, the matrix layer 161M is made of AlCu or Al.

Then, the insulating layer 161 and the current path 162 are formed inaccordance with a prescribed process. Various processes for theformation of the insulating layer 161 and the current path 162 can beexemplified as described below.

First of all, ion beams of inert gas such as Ar are irradiated onto thematrix metallic layer 161M. The irradiation of ion beams corresponds toa pre-treatment for the formation the insulating layer 161 and thecurrent path 162 and is called as a “PIT (Pre-ion treatment)”. Theportion of the bottom metallic layer is pumped up and infiltrated intothe matrix metallic layer 161M. In this way, such an energetic treatmentas the PIT for the matrix metallic layer 161M is important.

The metallic layer 15 of Cu and the matrix layer 21LM of the adhesionenhancing layer are formed two-dimensionally, but the Cu element of themetallic layer 15 and the matrix element of the matrix layer 21LM arepumped up and infiltrated into the matrix metallic layer 161M of AlCuthrough the PIT process. The Cu element infiltrated into the matrixmetallic layer 161M remains the same after post-oxidization, therebyforming the current path 162. The matrix element 21LM infiltrated intothe matrix metallic layer 161M is segregated from the Cu element afterthe post-oxidization but not segregated at the PIT process. The PITprocess is important for the formation of the current path made of highpurity Cu.

In the PIT process, for example, the Ar ion beams are irradiated underthe condition that the accelerating voltage is set within 30 to 150 V,the beam current is set within 20 to 200 mA and the treatment period oftime is set within 30 to 180 seconds. The accelerating voltage ispreferably set within 40 to 60 V. If the accelerating voltage is setbeyond the above-described range, the PIT process may induce the surfaceroughness for the assembly under fabrication, thereby deteriorating theMR ratio. The beam current is preferably set within 30 to 80 mA and thetreatment period of time is preferably set within 60 to 150 seconds.

The adhesion enhancing layer 21L and the current path 162 may be formedby means of biasing sputtering for the matrix metallic layer 161M beforethe conversion to the insulating layer 161 instead of the PIT process.With the DC biasing, the energy of the biasing sputtering is configuredsuch that the DC biasing voltage is set within 30 to 200 V. With the RFbiasing, the energy of the biasing sputtering is configured such thatthe RF biasing power is set within 30 to 200 W.

Then, an oxidizing gas is supplied so as to oxidize the matrix metalliclayer 161M, thereby forming the insulating layer 161. In this case, theoxidizing condition is appropriately controlled so as not to oxidize thecurrent path 162. According to the oxidizing process, the matrixmetallic layer 161M is converted into the insulating layer 161 of Al₂O₃and the current path 162 is formed through the insulating layer 161,thereby forming the CCP-NOL layer 16. In the oxidizing process, thematrix material 21LM to compose the adhesion enhancing layer is pumpedup with the Cu element of the current path, and then, concentrated atthe interface between the insulating layer 161 of Al₂O₃ and the currentpath 162 of Cu, thereby forming the adhesion enhancing layer 21L. Thematrix material 21LM located below the insulating layer 161 constitutesthe adhesion enhancing layer 21L as it is.

The oxidizing process can be conducted by supplying the oxidizing gasunder the condition that ion beams of inert gas (Ar, Xe, Kr, He) areirradiated onto the matrix metallic layer 161M (Ion beam-assistedOxidation: IAO). The spacer layer 16 containing the insulating layer 161of Al₂O₃ and the current path 162 of Cu is formed through the oxidizingprocess. The oxidizing process utilizes the characteristics of Al and Cufor oxidization. Generally, Al is likely to be oxidized and Cu is notlikely to be oxidized.

In the oxidizing process, for example, the Ar ion beams are irradiatedunder the condition that the accelerating voltage is set within 40 to200 V, the beam current is set within 30 to 200 mA and the treatmentperiod of time is set within 15 to 300 seconds while the oxygen gas issupplied. The accelerating voltage is preferably set within 50 to 100 V.If the accelerating voltage is set beyond the above-described range, thePIT process may induce the surface roughness for the assembly underfabrication, thereby deteriorating the MR ratio. The beam current ispreferably set within 40 to 100 mA and the treatment period of time ispreferably set within 30 to 180 seconds.

In the oxidizing process using the IAO, the amount of oxygen is setpreferably within 2000 to 4000 L (Langmuir) because it is not desiredthat the bottom magnetic layer (pinned layer 14) is oxidized in additionto the elemental Al of the matrix metallic layer 161M, which leads tothe deterioration of the thermal robustness and reliability of theCCP-CPP element. In view of the enhancement of the reliability of theCCP-CPP element, it is important that the magnetic layer (pinned layer14) under the spacer layer 16 is not oxidized so as to maintain themetallic property thereof. In this point of view, the amount of oxygento be supplied is preferably set within the above-described range.

In order to form the stable oxide by supplying the oxygen, it is desiredthat the oxygen is supplied only while the ion beams are irradiated ontothe assembly under fabrication. In other words, it is desired that theoxygen is not supplied while the ion beams are not irradiated.

The thickness of the bottom metallic layer 15 of Cu is controlled inaccordance with the thickness of the matrix metallic layer 161M of AlCu.Namely, if the thickness of the matrix metallic layer 161M is increased,the thickness of the bottom metallic layer 15 is required to beincreased so as to infiltrate much amount of elemental Cu composing thebottom metallic layer 15 into the matrix metallic layer 161M in the PITprocess. For example, when the thickness of the matrix metallic layer161M is set within 0.6 to 0.8 nm, the thickness of the bottom metalliclayer 15 is set within 0.1 to 0.5 nm. When the thickness of the matrixmetallic layer 161M is set within 0.8 to 1 nm, the thickness of thebottom metallic layer 15 is set within 0.3 to 1 nm. If the bottommetallic layer 15 is formed too thin, the sufficient amount of elementalCu can not be supplied into the matrix metallic layer 161M in the PITprocess, so that it is difficult to form the current path 162 throughthe matrix metallic layer 161M. As a result, the area resistance RA ofthe resultant magneto-resistance effect element may be much increasedand the MR ratio may be deteriorated.

In contrast, If the bottom metallic layer 15 is formed too thick, thesufficient amount of elemental Cu can be supplied into the matrixmetallic layer 161M in the PIT process, but the thick remnant Cu layermay be formed from the bottom metallic layer between the pinned layer 14and the spacer layer 16. In order to realize the high MR ratio in theCPP-CPP element, it is required that the current confined through thespacer layer 16 is flowed to the magnetic layer (the pinned layer 14 orthe free layer 18) as it is. If the thick Cu layer remains between thepinned layer 14 and the spacer layer 16, the current confined throughthe spacer layer 16 is extended in the vicinity of the pinned layer 14,resulting in the deterioration of the MR ratio. In this point of view,it is desired that the thickness of the remnant Cu layer is set to 1 nmor below after the completion of the intended magneto-resistance effectelement. If the thickness of the Cu layer is set beyond theabove-described range, the current confinement effect is diminished andthus, the MR ratio may not be enhanced. Preferably, the thickness of theCu layer is set to 0.6 nm or below.

The current path 162 may be made of another material such as Au or Aginstead of Cu. However, it is desired that the current path 162 is madeof Cu because the Cu current path 162 can exhibit a larger thermalstability against a given thermal treatment in comparison with an Au orAg current path.

If the current path 162 is made of the same magnetic material as thepinned layer 14, the metallic supplier (first metallic layer) for thecurrent path 162 is not required to be formed on the pinned layer 14.Namely, a second metallic layer to be converted into the insulatinglayer 161 is formed on the pinned layer 14, and the element composingthe pinned layer 14 is infiltrated into the second metallic layerthrough the PIT process, thereby forming the current path 162 made ofthe magnetic material of the pinned layer 14.

If the matrix layer 162M is made of Al₉₀Cu₁₀, the elemental Cu of thematrix layer 162M is segregated from the elemental Al thereof and theelemental Cu is pumped up from the first metallic layer in the PITprocess. Namely, the current path 162 is formed by the first and secondmetallic layers. If the ion beam-assisted oxidation is carried out afterthe PIT process, the separation between the elemental Al and theelemental Cu is developed and then, the oxidation for the elemental Alis developed.

When the matrix layer 162M is made of AlCu, the thickness of the matrixlayer 162M is set within 0.6 to 2 nm. When the matrix layer 162M is madeof Al, the thickness of the matrix layer 162M is set within 0.5 to 1.7nm. The thickness of the insulating layer 161 converted throughoxidation from the second metallic layer formed from the matrix layer162M is set within 0.8 to 3.5 nm. Particularly, the insulating layer 161with a thickness of 1.3 to 2.5 nm can be easily formed and thus, exhibitsome advantages for the current confinement effect. The diameter of thecurrent path 162 through the insulating layer 161 is within a range of 1to 10 nm, preferably within a range of 2 to 6 nm. If the diameter of thecurrent path 162 is beyond 10 nm, the characteristics of the intendedmagneto-resistance effect element may fluctuated due to the large sizeof the current path 162 as the magneto-resistance effect element isdownsized. In this point of view, it is desired that the current path162 with a diameter of 6 nm or over is not formed.

In this embodiment, in order to realize the current path 162 under goodcondition, the formation process of the current path 162 using thePIT/IAO treatment was described. However, the current path 162 can beformed under good condition by means of ion beam treatment using ionbeams of inert gas such as Ar, Xe, Kr or plasma treatment using inertgas plasma instead of the PIT process after the IAO process. Theformation process is called as an “AIT (After-ion treatment)” becausethe ion beam treatment or the plasma treatment is carried out after theoxidation. In other words, the current path 162 can be formed by meansof the IAO/AIT treatment.

With the PIT treatment, the elemental Cu is segregated from theelemental Al before oxidation. With the AIT treatment, the elemental Alis oxidized into Al₂O₃ by means of the IAO, and then, the elemental Cuis segregated from the Al₂O₃. The segregation is enhanced by the energyapplication from the ion beam irradiation or the plasma irradiation.

Moreover, by AIT process, if the current path 162 is partially oxidized,the oxidized portion of the current path 162 can be reduced. Forexample, in the case that the current path 162 is made of Cu, if thecurrent path 162 is partially oxidized to be converted into a CuOxcompound through the IAO treatment, the CuOx compound is reduced bymeans of the AIT treatment to be converted into the correspondingmetallic Cu.

In the AIT treatment, the ion beams of inert gas such as Ar, Kr, He, Ne,Xe are irradiated onto the second metallic layer under the conditionthat the accelerating voltage is set within 50 to 200 V, the current isset within 30 to 300 mA and the treatment period of time is set within30 to 180 seconds. Or the plasma (e.g., RF plasma) of inert gas iscontacted with the second metallic layer.

With the AIT treatment using the ion beams, the accelerating voltage andthe current can be controlled independently. With the AIT treatmentusing the plasma, the accelerating voltage and the current aredetermined simultaneously from the RF input power and thus, can not bealmost controlled independently. With the AIT treatment using theplasma, however, the maintenance of the apparatus to be employed for theAIT treatment can be simplified. In the AIT treatment, therefore, theion beams or the plasma can be appropriately selected in view of theabove-described advantages and disadvantages.

The AIT treatment requires an energy treatment larger than the PITtreatment after oxidation, so that the interlayer coupling field betweenthe pinned layer 14 and the free layer 18 is likely to be large becausethe surface roughness of the insulating layer 161 of the spacer layer 16becomes conspicuous by the AIT treatment to increase the Neel coupling(Orange peel coupling). With the PIT treatment, such a problem asdescribed above can be prevented. In this point of view, the PITtreatment is preferable.

The AIT treatment can be combined with the PIT treatment. In this case,three treatments of PIT/IAO/AIT may be conducted.

In this case, it is desired that the AIT treatment is conducted using alower energy in comparison with the AIT treatment in the oxidizingtreatment such as the PIT/IAO treatment without the PIT treatment so asto remove small amount of floating oxygen absorbed in the secondmetallic layer after the IAO treatment. The AIT treatment in thePIT/IAO/AIT treatment can be conducted under the condition that theaccelerating voltage is set within 50 to 100 V, the current is setwithin 30 to 20 mA and the treatment period of time is set within 10 to120 seconds while the ion beams of inert gas such as Ar, Kr, He, Ne, Xeare irradiated or the plasma (RF plasma) of inert gas is contacted.

Then, the top metallic layer 17 is formed, e.g., as a Cu layer with athickness of 0.25 nm on the CCP-NOL layer 16 (S4-a5). Preferably, thethickness of the top metallic layer 17 is set within 0.2 to 0.6 nm. Ifthe thickness of the top metallic layer 17 is set to about 0.4 nm, thecrystallinity of the free layer 18 can be easily enhanced. Since thecrystallinity of the free layer 18 can be controlled by adjusting thefilm-forming condition, the top metallic layer 17 may be omitted asoccasion demands.

The adhesion enhancement can be conducted by another means using plasmaor ion beam as an adhesion enhancing treatment instead of the formationof the adhesion enhancing layer. For example, the plasma treatment orthe ion beam treatment is conducted so as to develop the roughness atthe interface between the adjacent layers and thus, increase thecontacting area between the adjacent layers. In this case, the adhesionbetween the adjacent layers can be enhanced by the increase of thecontacting area. Moreover, the intermixing between the adjacent layerscan be conducted by the plasma treatment or the ion beam treatment so asto much enhance the adhesion between the adjacent layers.

Concretely, the plasma treatment is conducted by contacting a plasma ofinert gas with the interface between the adjacent layers before theupper layer is formed. The ion beam treatment is conducted byirradiating ion beams of inert gas onto the interface between theadjacent layers before the upper layer is formed. As the inert gas, Ar,Xe, Kr, He, Ne can be exemplified. In view of the manufacturing cost, Aris preferable as the inert gas. Of course, Xe with larger mass than Armay be employed as occasion demands. The use of Xe can exhibit theinherent characteristics.

The adhesion enhancing treatment can be combined with the formation ofthe adhesion enhancing layer so as to much enhance the intended adhesionbetween the adjacent layers. In the case that the adhesion enhancingtreatment is combined with the process as shown in FIG. 6, the adhesionenhancing treatment is conducted for the surface of the bottom metalliclayer 15 or the surface of the metallic layer 21LM mainly composing theadhesion enhancing layer.

The adhesion enhancing treatment can be combined with the formation ofan adhesion enhancing layer which is formed at another interface asdescribed below.

FIG. 7 shows the formation process of the adhesion enhancing layer 21Uas shown in FIG. 3 in detail. In this process, the matrix layer of theadhesion enhancing layer is formed and then, the CCP-NOL layer formingprocess is conducted for the matrix layer, thereby forming the adhesionenhancing layer at the interface between the insulating layer 161 andthe metallic layer 17.

First of all, the metallic layer 15 is formed, e.g., as a Cu layer(S14-b1). Then, the matrix layer 161M mainly composing the CCP-NOL layeris formed (S14-b2). In this case, since the insulating layer 161 is madeof Al₂O₃, the matrix layer 161M is made of AlCu or Al.

Then, the matrix metallic layer 21UM of the adhesion enhancing layer isformed (S14-b3). The matrix metallic layer 21UM may contain an elementwith an oxide formation energy higher than the oxide formation energy ofthe element composing the matrix layer of the insulating layer 161 andlower than the oxide formation energy of the element composing themetallic layers 17. Referring to Table 1, when the insulating layer 161is made of Al₂O₃, the resultant adhesion enhancing layer 21L may containSi, Hf, Ti, V, W, Mg, Mo, Cr or Zr.

Then, the insulating layer 161 and the current path 162 are formed(S14-b4). In the process, the metallic layer 21U is formed from thematrix metallic layer 21UM on the top surface of the insulating layer161 during the formation of the insulating layer 161 and the currentpath 162.

Then, the top metallic layer 17 is formed, e.g., as the Cu layer with athickness of 0.25 nm on the resultant CCP-NOL layer 16 (S14-b5). Thethickness of the top metallic layer 17 is preferably set within 0.2 to0.6 nm. If the thickness of the top metallic layer 17 is set to about0.4 nm, the crystallinity of the free layer 18 can be easily enhanced.Since the crystallinity of the free layer 18 can be controlled byadjusting the film-forming condition, the top metallic layer 17 may beomitted as occasion demands.

Without the top metallic layer 17, the adhesion enhancing layer 21U isformed between the insulating layer 161 and the free layer 18. The maincomponent element of the free layer 18 is Co, Fe and/or Ni. In thiscase, in order to exhibit the inherent function (adhesion enhancement)of the adhesion enhancing layer 21U, it is required that the elementcomposing the adhesion enhancing layer 21U has a larger oxide formationenergy than the one of the element(s) composing the free layer 18.Referring to Table 1, since an element such as Al, Si, Hf, Ti, V, W, Mg,Mo, Cr or Zr is larger in oxide formation energy than Co, Fe and Ni, theexemplified element can be used as a component element for the adhesionenhancing layer.

FIG. 8 also shows the formation process of the adhesion enhancing layer21U as shown in FIG. 3 in detail. In this process, the CCP-NOL layerforming process is conducted and then, the matrix layer of the adhesionenhancing layer is formed, thereby forming the adhesion enhancing layerat the interface between the insulating layer 161 and the metallic layer17.

First of all, the metallic layer 15 is formed, e.g., as a Cu layer(S14-c1). Then, the matrix layer 161M mainly composing the CCP-NOL layeris formed (S14-c2). In this case, since the insulating layer 161 is madeof Al₂O₃, the matrix layer 161M is made of AlCu or Al. Then, theinsulating layer 161 and the current path 162 are formed (S14-c3).

Then, the matrix metallic layer 21UM′ of the adhesion enhancing layer isformed (S14-c4). The matrix metallic layer 21UM′ may contain an elementwith an oxide formation energy higher than the oxide formation energy ofthe element composing the matrix layer of the insulating layer 161 andlower than the oxide formation energy of the element composing themetallic layers 17. In this case, however, the matrix metallic layer maycontain the same component element as the component element of theinsulating layer 161, which will be described in detail, hereinafter. Inthis step, the adhesion enhancing layer 21U is formed from the metalliclayer 21UM′ on the insulating layer 161.

The reason the adhesion enhancing layer 21U′ may contain the samecomponent element as the component element of the insulating layer 161will be described. In the process as shown in FIG. 8, since the matrixmetallic layer 21 of the adhesion enhancing layer 21U′ is formed afterthe oxidation for the matrix layer 161M of the insulating layer 161, thecoupling between the elemental Al and the elemental oxygen of theinsulating layer 161 is strengthened. In this point of view, if theadhesion enhancing layer 21U′ contains the elemental Al, the elementaloxygen of the insulating layer 161, e.g., made of Al₂O₃, is unlikely tobe moved into the adhesion enhancing layer 21U′ so that the content inoxygen of the adhesion enhancing layer 21U′ becomes different from thecontent in oxygen of the insulating layer 161. As a result, the contentin oxygen of the adhesion enhancing layer 21U′ can be reduced in thevicinity of the metallic layer to be formed on the adhesion enhancinglayer 21U′.

Then, the top metallic layer 17 is formed, e.g., as the Cu layer with athickness of 0.25 nm on the resultant CCP-NOL layer 16 (S14-c5). Thethickness of the top metallic layer 17 is preferably set within 0.2 to0.6 nm. If the thickness of the top metallic layer 17 is set to about0.4 nm, the crystallinity of the free layer 18 can be easily enhanced.Since the crystallinity of the free layer 18 can be controlled byadjusting the film-forming condition, the top metallic layer 17 may beomitted as occasion demands.

Without the top metallic layer 17, the adhesion enhancing layer 21U′ isformed between the insulating layer 161 and the free layer 18. The maincomponent element of the free layer 18 is Co, Fe and/or Ni. In thiscase, in order to exhibit the inherent function (adhesion enhancement)of the adhesion enhancing layer 21U′, it is required that the elementcomposing the adhesion enhancing layer 21U′ has a larger oxide formationenergy than the one of the element(s) composing the free layer 18.Referring to Table 1, since an element such as Al, Si, Hf, Ti, V, W, Mg,Mo, Cr or Zr is larger in oxide formation energy than Co, Fe and Ni, theexemplified element can be used as a component element for the adhesionenhancing layer 21U′.

FIG. 9 shows the formation process of the adhesion enhancing layers 21Land 21U as shown in FIG. 4 in detail. In this process, the matrix layerof the adhesion enhancing layer is formed according to the process asshown in FIG. 7 and then, the CCP-NOL layer forming process is conductedfor the matrix layer, thereby forming the adhesion enhancing layers 21Land 21U at the interfaces between the insulating layer 161 and themetallic layers 15, 17.

First of all, the metallic layer 15 is formed, e.g., as a Cu layer(S14-d1). Then, the matrix metallic layer 21LM of the adhesion enhancinglayer 21L is formed (S14-d2). The matrix metallic layer 21LM may containan element with an oxide formation energy higher than the oxideformation energy of the element composing the matrix layer of theinsulating layer 161 and lower than the oxide formation energy of theelement composing the metallic layers 15. Referring to Table 1, when theinsulating layer 161 is made of Al₂O₃, the resultant adhesion enhancinglayer 21L may contain Si, Hf, Ti, V, W, Mg, Mo, Cr or Zr.

Then, the matrix metallic layer 161M of the CCP-NOL layer 16 is formed(S14-d3). In this case, since the insulating layer 161 is made of Al₂O₃,the matrix metallic layer 161M is made of AlCu or Al.

Then, the matrix metallic layer 21UM of the adhesion enhancing layer 21Uis formed (S14-d4). The matrix metallic layer 21UM may contain anelement with an oxide formation energy higher than the oxide formationenergy of the element composing the matrix layer of the insulating layer161 and lower than the oxide formation energy of the element composingthe metallic layers 17. In this case, since the insulating layer 161 ismade of Al₂O₃, the matrix metallic layer 161M is made of AlCu or Al.

Then, the insulating layer 161 and the current path 162 are formed(S14-d5). In the process, the metallic layers 21L and 21U are formedfrom the matrix metallic layers 21LM and 21UM so as to cover theinsulating layer 161 during the formation of the insulating layer 161and the current path 162.

FIG. 10 also shows the formation process of the adhesion enhancinglayers 21L and 21U as shown in FIG. 4 in detail. In this process, thematrix layer of the adhesion enhancing layer is formed according to theprocess as shown in FIG. 7 and then, the CCP-NOL layer forming processis conducted for the matrix layer, thereby forming the adhesionenhancing layers 21L at the interface between the insulating layer 161and the metallic layers 15. Then, the adhesion enhancing layer 21U′ isformed at the interface between the insulating layer 161 and themetallic layer 17 according to the process as shown in FIG. 8.

First of all, the metallic layer 15 is formed, e.g., as a Cu layer(S14-e1). Then, the matrix metallic layer 21LM of the adhesion enhancinglayer 21L is formed (S14-e2). The matrix metallic layer 21LM may containan element with an oxide formation energy higher than the oxideformation energy of the element composing the matrix layer of theinsulating layer 161 and lower than the oxide formation energy of theelement composing the metallic layers 15. Referring to Table 1, when theinsulating layer 161 is made of Al₂O₃, the resultant adhesion enhancinglayer 21L may contain Si, Hf, Ti, V, W, Mg, Mo, Cr or Zr.

Then, the matrix metallic layer 161M of the CCP-NOL layer 16 is formed(S14-e3). In this case, since the insulating layer 161 is made of Al₂O₃,the matrix metallic layer 161M is made of AlCu or Al.

Then, the insulating layer 161 and the current path 162 are formed(S14-e4). In the process, the adhesion enhancing 21L is formed from thematrix metallic layer 21LM at the interface between the insulating layer161 and the metallic layer 15 and the interface between the insulatinglayer 161 and the current path 162.

Then, the matrix metallic layer 21UM′ of the adhesion enhancing layer21U′ is formed (S14-d4). The matrix metallic layer 21UM′ may contain anelement with an oxide formation energy higher than the oxide formationenergy of the element composing the matrix layer of the insulating layer161 and lower than the oxide formation energy of the element composingthe metallic layers 17. Moreover, the matrix metallic layer 21UM′ maycontain the same component element as the component element of theinsulating layer 161 on the same reason relating to the process as shownin FIG. 8. In this step, the adhesion enhancing layer 21U′ is formedfrom the metallic layer 21UM′ on the insulating layer 161.

(Apparatus to be Employed for Manufacturing a Magneto-Resistance EffectElement)

FIG. 11 is a schematic view illustrating a film forming apparatus formanufacturing a magneto-resistance effect element according to thepresent invention. As shown in FIG. 11, the transfer chamber (TC) 50 isdisposed at the center of the apparatus such that the load lock chamber51, the pre-cleaning chamber 52, the first metallic film-forming chamber(MC1) 53, the second metallic film-forming chamber (MC2) 54 and theoxide layer-nitride layer forming chamber (OC) 60 are disposed so as tobe connected with the transfer chamber 50 via the gate valves,respectively. In the apparatus, the substrate on which various films areto be formed is transferred from one chamber from another chamber underthe vacuum condition via the corresponding gate valve. Therefore, thesurface of the substrate can be maintained clean.

The metallic film-forming chambers 53 and 54 include a plurality oftargets (five to ten targets) which is called as a multi-structuredtarget. As the film forming means, a sputtering method such as a DCmagnetron sputtering or an RF magnetron sputtering, an ion beamsputtering, a vacuum deposition, a CVD (Chemical Vapor Deposition) or anMBE (Molecular Beam Epitaxy) can be employed.

(Schematic Explanation of the Method for Manufacturing aMagneto-Resistance Effect Element)

Hereinafter, the method for manufacturing a magneto-resistance effectelement will be schematically described. First of all, on the substrate(not shown) are subsequently formed the bottom electrode 11, theunderlayer 12, the pinning layer 13, the pinned layer 14, the bottommetallic layer 15, the spacer layer 16, the top metallic layer 17, thefree layer 18, the cap layer 19 and the top electrode 20.

A substrate is set into the load lock chamber 51 so that some metallicfilms are formed in the metallic film-forming chambers 53 and 54 andsome oxide and/or nitride layers are formed in the oxide layer-nitridelayer forming chamber 60. The ultimate vacuum of the metallicfilm-forming chambers 53 and 54 is preferably set to 1×10⁻⁸ Torr orbelow, normally within a range of 5×10⁻¹⁰ Torr to 5×10⁻⁹ Torr. Theultimate vacuum of the transfer chamber 50 is set in the order of 10⁻⁹Torr. The ultimate vacuum of the oxide layer-nitride layer formingchamber 60 is set to 8×10⁻⁸ Torr or below.

(1) Formation of Underlayer 12 (Step S11)

The bottom electrode 11 is formed on the (not shown) substrate by meansof micro-process in advance. Then, the underlayer 12 is formed as alayer of Ta 5 nm/Ru 2 nm on the bottom electrode 11. The Ta layerfunctions as the buffer layer 12 a for relaxing the surface roughness ofthe bottom electrode 11. The Ru layer functions as the seed layer 12 bfor controlling the crystalline orientation and the crystal grain of thespin valve film to be formed thereon.

(2) Formation of Pinning Layer 13 (Step S12)

Then, the pinning layer 13 is formed on the underlayer 12. The pinninglayer 13 may be made of an antiferromagnetic material such as PtMn,PdPtMn, IrMn, RuRhMn.

(3) Formation of Pinned Layer 14 (Step S13)

Then, the pinned layer 14 is formed on the pinning layer 13. The pinnedlayer 14 may be formed as the synthetic pinned layer of the bottompinned layer 141 (Co₉₀Fe₁₀)/the magnetic coupling layer 142 (Ru)/the toppinned layer 143 (Co₉₀Fe₁₀).

(4) Formation of CCP-NOL Layer 16 (Step S14)

Then, the CCP-NOL layer 16 with the current-confined-path structure (CCPstructure) is formed in the oxide layer-nitride layer forming chamber60. The CCP-NOL layer 16 can be formed in the same manner as “Method formanufacturing a magneto-resistance effect element”. By forming theadhesion enhancing layer at the interface between the insulating layer161 and the metallic layer 15, the current path 162 or at the interfacebetween the insulating layer 161 and the metallic layer 17 or the freelayer 18, the reliability of the magneto-resistance effect element canbe developed.

(5) Formation of Free Layer 18 (Step S15)

In order to realize the higher MR ratio of the magneto-resistance effectelement, the appropriate material selection for the free layer 18 in thevicinity of the spacer 16 should be considered. In this point of view,it is desired to form the NiFe alloy film or the CoFe alloy film at theinterface between the free layer 18 and the spacer layer 16. The CoFealloy film is more preferable than the NiFe alloy film. As the CoFealloy film, the Co₉₀Fe₁₀ layer with a thickness of 1 nm can beexemplified. Of course, the CoFe alloy layer can contain anthercomposition.

If the CoFe alloy layer with a composition almost equal to the one ofthe Co₉₀Fe₁₀ layer is employed, the thickness of the CoFe alloy layer ispreferably set within 0.5 to 4 nm. If the CoFe alloy layer with acomposition (e.g., Co₅₀Fe₅₀) different from the one of the Co₉₀Fe₁₀layer is employed, the thickness of the CoFe alloy layer is preferablyset within 0.5 to 2 nm. If the free layer 18 is made of Fe₅₀Co₅₀ (orFe_(x)Co_(100-x) (X=45˜85)) in view of the enhancement in spin dependentinterface scattering effect, it is difficult to set the thickness of thefree layer 18 as thick as the pinned layer 14 so as to maintain the softmagnetism of the free layer 18. In this case, therefore, the thicknessof the free layer 18 is preferably set within 0.5 to 1 nm. If the freelayer 18 is made of Fe or Fe alloy without Co, the thickness of the freelayer 18 may be increased within 0.5 to 4 nm because the soft magnetismof the free layer can be maintained under good condition.

The NiFe alloy layer can maintain stably the inherent soft magnetism,but the CoFe alloy layer can not maintain stably inherent soft magnetismin comparison with the NiFe alloy layer. In this case, if the NiFe alloylayer is formed on the CoFe alloy layer, the soft magnetism of the CoFealloy can be compensated with the soft magnetism of the NiFe alloylayer. In this point of view, the formation of the NiFe alloy layer atthe interface between the free layer 18 and the spacer layer 16 candevelop the MR ratio of the spin valve film, that is, themagneto-resistance effect element.

The composition of the NiFe alloy layer is preferably set toNi_(x)Fe_(100-x) (X=75 to 85%). Particularly, the composition of theNiFe alloy layer is preferably set to a Ni-rich composition incomparison with the normal composition of Ni₈₁Fe₁₉ (e.g., Ni₈₃Fe₁₇) soas to realize the non-magnetostriction of the NiFe layer. Themagnetostriction of the NiFe alloy layer is shifted positive when theNiFe alloy layer is formed on the CCP-structured spacer 16 in comparisonwith the magnetostriction of the NiFe alloy layer when the NiFe alloylayer is formed on a Cu spacer. In this point of view, the compositionof the NiFe alloy layer is shifted to a Ni-rich composition in advanceso as to cancel the positive magnetostriction of the NiFe alloy layerformed on the spacer layer 16 because the Ni-rich NiFe alloy layer canexhibit the negative magnetostriction.

The thickness of the NiFe layer may be set preferably within 2 to 5 nm(e.g., 3.5 nm). Without the NiFe layer, a plurality of CoFe layers or Felayers with a thickness of 1 to 2 nm and a plurality of thinner Culayers with a thickness of 0.1 to 0.8 nm are alternately stacked oneanother, thereby forming the free layer 18.

(6) Formation of Cap Layer 19 and Top Electrode (Step S16)

The cap layer 19 is formed as a multilayer of Cu 1 nm/Ru 10 nm on thefree layer 18. Then, the top electrode 20 is formed on the cap layer 19so as to flow a current to the spin valve film in the directionperpendicular to the film surface thereof.

EXAMPLES

The present invention will be described in detail in view of Examples.

Example 1

Bottom electrode 11 Underlayer 12 Ta 5 nm/Ru 2 nm Pinning layer 13Ir₂₂Mn₇₈ 7 nm Pinned layer 14 Co₇₅Fe₂₅ 3.2 nm/Ru 0.9 nm/Fe₅₀Co₅₀ 1 nm/Cu0.25 nm × 2/Fe₅₀C₅₀ 1 nm Metallic layer 15 Cu 0.5 nm CCP-NOL layer 16adhesion enhancing layer composed of insulating layer 161 of Al₂O₃,current path 162 of Cu and Ti layer (the multilayer of Ti 0.25nm/Al₉₀Cu₁₀ 1 nm/Ti 0.25 nm is formed and treated by means of PIT/IAO)Metallic layer 17 Cu 0.25 nm Free layer 18 Co₉₀Fe₁₀ 1 nm/Ni₈₃Fe₁₇ 3.5 nmCap layer 19 Cu 1 nm/Ru 10 nm Top electrode 20

The manufacturing process of the CCP-NOL layer 16 will be described. Themanufacturing processes of other layers can be conducted by means ofconventional techniques and thus, will be omitted.

First of all, the metallic layer 15 was formed as a Cu layer with athickness of 0.5 nm. Then, the matrix metallic layer of the adhesionenhancing layer was formed as a Ti layer with a thickness of 0.25 nm.The Ti layer constitutes the lower portion of the adhesion enhancinglayer, and has an oxide formation energy higher than the elemental Almainly composing the matrix material Al₉₀Cu₁₀ of the CCP-NOL layer andlower than the elemental Cu of the metallic layer 15. Instead of the Tilayer, the matrix metallic layer of the adhesion enhancing layer may bemade of Si, Hf, V, W, Mg, Mo, Cr, Nb or Zr.

Then, the Al₉₀Cu₁₀ layer with a thickness of 1 nm as the matrix materialAl₂O₃ of the insulating layer was formed. Then, the Ti layer with athickness of 0.25 nm as the matrix material constituting the upperportion of the adhesion enhancing layer was formed. Then, the Al₂O₃insulating layer and the Cu current path 162 formation process wasconducted by means of PIT/IAO process.

Throughout the above-described process, in the CCP-NOL layer composed ofthe Al₂O₃ insulating layer 161, the Cu current path 162, the intendedadhesion enhancing layer was formed at the interface between theinsulating layer 161 and the metallic layer 15, at the interface betweenthe insulating layer 161 and the current path 162 and at the interfacebetween the insulating layer 161 and the metallic layer 17.

When the resultant magneto-resistance effect element (CCP-CPP element)10 was observed by means of three-dimensional atomic probe, it wasconfirmed that the adhesion enhancing layer containing elemental Ti as amain component was formed at the interface between the insulating layer161 and the adjacent metallic layers.

Then, the various characteristics of the CCP-CPP element wereinvestigated. As a result, the element resistance RA was 500 mΩ/μm, theMR ratio was 9% and the element resistance variation ΔRA was 45 mΩ/μm².These characteristics are almost equal to the ones of a CCP-CPP elementwithout the adhesion enhancing layer.

Then, the reliability of the CCP-CPP element was investigated. Thecurrent flow test was carried out under the condition that thetemperature was 130° C., and the biasing voltage was 140 mV. In thisinvestigation, the current flow condition was set to a severe one so asto obtain the result in the current flow test of the CCP-CPP elementimmediately. The current flow direction was set so that the current wasflowed from the pinned layer 14 to the free layer 18. In this case, theelectron flow was generated from the free layer 18 to the pinned layer14 opposite of the current direction.

The current flow direction is favorable for the reduction of the spintransfer noise. Allegedly, the spin transfer effect becomes large whenthe current is flowed from the free layer 18 to the pinned layer 14 (theelectron flow is generated from the pinned layer 14 to the free layer18), which leads to the noise generation in the CCP-CPP element. In thispoint of view, it is desired that the current is flowed from the pinnedlayer to the free layer.

As described above, the test condition was set to a severe one for theacceleration of the reliability test for the CCP-CPP element. In thisembodiment, the chip size of the CCP-CPP element to be employed in amagnetic head was set larger than a normal chip size (e.g., 0.1 μm×0.1μm). The amount of current flow is increased under a given biasingvoltage and thus, the heat radiation performance of the CCP-CPP elementmay be deteriorated as the chip size of the CCP-CPP element isincreased. In this point of view, in this embodiment, the thus generatedJoule heat affects the CCP-CPP element remarkably in comparison with thereal CCP-CPP element to be employed in the magnetic head. In view of theJoule heat, therefore, the reliability of the CCP-CPP element is testedunder a severe condition. If the biasing voltage is increased and thetesting temperature is increased, the reliability of the CCP-CPP elementresults in being tested under a more severe condition so as toaccelerate the reliability test and shorten the testing period of time.

When the current flow test was carried out under the severe acceleratingcondition, it was confirmed that the reliability of the CCP-CPP elementwas enhanced remarkably in comparison with a CCP-CPP element without theadhesion enhancing layer.

The higher reliability of the CCP-CPP element under the severe conditionin this embodiment means that the CCP-CPP element can be employed underan environmental condition requiring higher reliability. In view of theapplication of the CCP-CPP element to a high density recording head, thereliability of the recording head can be enhanced remarkably incomparison of a conventional high density recording head. Thus, the highdensity recording head can be applied for a car navigation systemrequiring a severe use condition such as high temperature environment orfor an HDD (Hard disk drive) of a server or an enterprise which isoperated at high speed.

Example 2

In this Example, the formation process of the adhesion enhancing layerto be formed on the insulating layer 161 was changed in comparison withExample 1. In Example 1, the matrix Ti layer of the adhesion enhancinglayer is formed at the upper interface for the insulating layer 161, andthen, treated by means of PIT/IAO process. In Example 2, the PIT/IAOprocess was conducted in advance and then, the matrix Ti layer of theadhesion enhancing layer was formed. In this case, the matrix layer ofthe adhesion enhancing layer can contain an element with an oxideformation energy almost equal to the oxide formation energy of theelement of the insulating layer 161, in addition to the element with alower oxide formation energy than the element of the insulating layer161 such as Ti, Al, Si, Hf, V, W, Mg, Mo, Cr or Zr.

When the resultant magneto-resistance effect element (CCP-CPP element)10 was observed by means of three-dimensional atomic probe, it wasconfirmed that the adhesion enhancing layer containing elemental Ti as amain component was formed at the interface between the insulating layer161 and the adjacent metallic layers.

Then, the various characteristics of the CCP-CPP element wereinvestigated. As a result, the element resistance RA was 500 mΩ/μm, theMR ratio was 9% and the element resistance variation ΔRA was 45 mΩ/μm².These characteristics are almost equal to the ones of a CCP-CPP elementwithout the adhesion enhancing layer. Then, when the current flow testwas carried out under the severe accelerating condition in the samemanner, it was confirmed that the reliability of the CCP-CPP element wasenhanced remarkably in comparison with a CCP-CPP element without theadhesion enhancing layer.

(Application of Magneto-Resistance Effect Element)

The application of the magneto-resistance effect element according tothis embodiment will be described hereinafter,

In view of high density recording, the element resistance RA is setpreferably to 500 mΩ/μm or below, more preferably to 300 mΩ/μm or below.In the calculation of the element resistance RA, the effective area A incurrent flow of the spin valve film is multiplied to the resistance R ofthe CPP-CPP element. Herein, the element resistance R can be directlymeasured, but attention should be paid to the effective area A becausethe effective area A depends on the element structure.

If the whole area of the spin valve film is effectively sensed bycurrent through patterning, the whole area of the spin valve filmcorresponds to the effective area A. In this case, the whole area of thespin valve film is set to 0.04 μm² or below in view of the appropriateelement resistance, and to 0.02 μm² or below in view of the recordingdensity of 200 Gbpsi or over.

If the area of the bottom electrode 11 or the top electrode 20 is setsmaller than the whole area of the spin valve film, the area of thebottom electrode 11 or the top electrode 20 corresponds to the effectivearea A. If the area of the bottom electrode 11 is different from thearea of the top electrode 20, the smaller area of either of the bottomelectrode 11 or the top electrode 20 corresponds to the effective areaA. As described above, the smaller area is set to 0.04 μm² or below inview of the appropriate element resistance

Referring to FIGS. 12 and 13, since the smallest area of the spin valvefilm 10 corresponds to the contacting area with the top electrode 20 asapparent from FIG. 12, the width of the smallest area can be consideredas a track width Tw. Then, since the smallest area of the spin valvefilm 10 in MR height direction also corresponds to the contacting areawith the top electrode 20 as apparent from FIG. 13, the width of thesmallest are can be considered as a height length D. In this case, theeffective area A can be calculated on the equation of A=Tw×D.

In the magneto-resistance effect element according to this embodiment,the resistance R between the electrodes can be reduced to 100Ω or below,which corresponds to the resistance between the electrode pads in thereproducing head attached to the forefront of a head gimbal assembly(HGA), for example.

It is desired that the magneto-resistance effect element is structuredin fcc (111) orientation when the pinned layer 14 or the free layer 18has the fcc-structure. It is also desired that the magneto-resistanceeffect element is structured in bcc (100) orientation when the pinnedlayer 14 or the free layer 18 has the bcc-structure. It is also desiredthat the magneto-resistance effect element is structured in hcp (001)orientation when the pinned layer 14 or the free layer 18 has thehcp-structure.

The crystalline orientation of the magneto-resistance effect elementaccording to this embodiment is preferably 4.5 degrees or below, morepreferably 3.5 degrees or below and particularly 3.0 degrees or below inview of the dispersion of orientation. The crystalline orientation canbe measured from the FWHM of X-ray rocking curve obtained from the θ-2θmeasurement in X-ray diffraction. The crystalline orientation can bealso measured by the spot scattering angle originated from thenano-diffraction spots of the element cross section.

Depending on the kind of material of the antiferromagnetic film, sincethe lattice spacing of the antiferromagnetic film is different from thelattice spacing of the pinned layer 14/CCP-NOL layer 16/free layer 18,the dispersion in crystalline orientation can be obtained between theantiferromagnetic film and the pinned layer 14/CCP-NOL layer 16/freelayer 18. For example, the lattice spacing of the PtMn antiferromagneticlayer is often different from the lattice spacing of the pinned layer14/CCP-NOL layer 16/free layer 18. In this point of view, since the PtMnlayer is formed thicker, the PtMn layer is suitable for the measurementin dispersion of the crystal orientation. With the pinned layer14/CCP-NOL layer 16/free layer 18, the pinned layer 14 and the freelayer 18 may have the respective different crystal structures ofbcc-structure and fcc-structure. In this case, the dispersion angle incrystal orientation of the pinned layer 14 may be different from thedispersion angle in crystal orientation of the free layer 18.

(Magnetic Head)

FIGS. 12 and 13 are cross sectional views showing the state where themagneto-resistance effect element according to this embodiment isincorporated in a magnetic head. FIG. 12 is a cross sectional viewshowing the magneto-resistance effect element, taken on the surfacealmost parallel to the ABS (airbearing surface) opposite to a (notshown) magnetic recording medium. FIG. 13 is a cross sectional viewshowing the magneto-resistance effect element, taken on the surfacealmost perpendicular to the ABS.

The magnetic head shown in FIGS. 12 and 13 has a so-called hard abuttedstructure. The magneto-resistance effect film 10 is the CCP-CPP film asdescribed above. The bottom electrode 11 and the top electrode 20 areprovided on the top surface and the bottom surface of themagneto-resistance effect film 10, respectively. In FIG. 12, the biasingmagnetic applying films 41 and the insulating films 42 are formed at theboth sides of the magneto-resistance effect film 10. In FIG. 13, theprotective layer 43 is formed on the ABS of the magneto-resistanceeffect film 10.

The sense current is flowed along the arrow A through themagneto-resistance effect film 10 between the bottom electrode 11 andthe top electrode 20, that is, in the direction perpendicular to thefilm surface of the magneto-resistance effect film 10. Moreover, a givenbiasing magnetic field is applied to the magneto-resistance effect film10 from the biasing magnetic field applying films 41 so as to render thedomain structure of the free layer 18 of the film 10 a single domainstructure through the control of the magnetic anisotropy of the freelayer 18 and stabilize the magnetic domain structure of the free layer18. In this case, the Barkhausen noise due to the shift of magnetic wallin the magneto-resistance effect film 10 can be prevented.

Since the S/N ratio of the magneto-resistance effect film 10 isenhanced, the magnetic head including the magneto-resistance effect film10 can realize the high sensitive magnetic reproduction.

(Magnetic Head and Magnetic Recording/Reproducing Device)

The magneto-resistance effect element is installed in advance in anall-in-one magnetic head assembly allowing both therecording/reproducing, and mounted as the head assembly at the magneticrecording/reproducing device.

FIG. 14 is a perspective view illustrating the schematic structure ofthe magnetic recording/reproducing device. The magneticrecording/reproducing device 150 illustrated in FIG. 14 constitutes arotary actuator type magnetic recording/reproducing device. In FIG. 14,a magnetic recording disk 200 is mounted to a spindle 152 to be turnedin the direction designated by the arrow A by a motor (not shown) whichis driven in response to control signals from a drive unit controller(not shown). In FIG. 14, the magnetic recording/reproducing apparatus150 may be that provided with a single magnetic recording disk 200, butwith a plurality of magnetic recording disks 200.

A head slider 153 recording/reproducing information to be stored in themagnetic recording disk 200 is mounted on a tip of a suspension 154 of athin film type. The head slider 153 mounts at the tip the magnetic headcontaining the magnetic resistance effect element as described in aboveembodiments.

When the magnetic recording disk 200 is rotated, such a surface (ABS) ofthe head slider 153 as being opposite to the magnetic recording disk 200is floated from on the main surface of the magnetic recording disk 200.Alternatively, the slider may constitute a so-called “contact runningtype” slider such that the slider is in contact with the magneticrecording disk 200.

The suspension 154 is connected to one edge of the actuator arm 155 witha bobbin portion supporting a driving coil (not shown) and the like. Avoice coil motor 156 being a kind of a linear motor is provided at theother edge of the actuator arm 155. The voice coil motor 156 is composedof the driving coil (not shown) wound around the bobbin portion of theactuator arm 155 and a magnetic circuit with a permanent magnet and acounter yoke which are disposed opposite to one another so as tosandwich the driving coil.

The actuator arm 155 is supported by ball bearings (not shown) providedat the upper portion and the lower portion of the spindle 157 so as tobe rotated and slid freely by the voice coil motor 156.

FIG. 15 is an enlarged perspective view illustrating a portion of themagnetic head assembly positioned at the tip side thereof from theactuator arm 155, as viewed from the side of the magnetic recording disk200. As illustrated in FIG. 15, the magnetic head assembly 160 has theactuator arm 155 with the bobbin portion supporting the driving coil andthe like. The suspension 154 is connected with the one edge of theactuator arm 155. Then, the head slider 153 with the magnetic headcontaining the magneto-resistance effect element as defined inabove-embodiments is attached to the tip of the suspension 154. Thesuspension 154 includes a lead wire 164 for writing/reading signals,where the lead wire 164 is electrically connected with the respectiveelectrodes of the magnetic head embedded in the head slider 153. In thedrawing, reference numeral “165” denotes an electrode pad of theassembly 160.

In the magnetic recording/reproducing device illustrated in FIGS. 14 and15, since the magneto-resistance effect element as described in theabove embodiments is installed, the information magnetically recorded inthe magnetic recording disk 200 can be read out properly.

(Magnetic Memory)

The magneto-resistance effect element as described above can constitutea magnetic memory such as a magnetic random access memory (MRAM) wherememory cells are arranged in matrix.

FIG. 16 is a view illustrating an embodiment of the magnetic memorymatrix according to the present invention. This drawing shows a circuitconfiguration when the memory cells are arranged in an array. In orderto select one bit in the array, a column decoder 350 and a line decoder351 are provided, where a switching transistor 330 is turned ON by a bitline 334 and a word line-332 and to be selected uniquely, so that thebit information recorded in a magnetic recording layer (free layer) inthe magneto-resistance effect film 10 can be read out by being detectedby a sense amplifier 352. In order to write the bit information, awriting current is flowed in a specific write word line 323 and a bitline 322 to generate a magnetic field for writing.

FIG. 17 is a view illustrating another embodiment of the magnetic memorymatrix according to the present invention. In this case, a bit line 322and a word line 334 which are arranged in matrix are selected bydecoders 360, 361, respectively, so that a specific memory cell in thearray is selected. Each memory cell is configured such that themagneto-resistance effect film 10 and a diode D is connected in series.Here, the diode D plays a role of preventing a sense current fromdetouring in the memory cell other than the selected magneto-resistanceeffect film 10. A writing is performed by a magnetic field generated byflowing the writing current in the specific bit line 322 and the wordline 323, respectively.

FIG. 18 is a cross sectional view illustrating a substantial portion ofthe magnetic memory in an embodiment according to the present invention.FIG. 19 is a cross sectional view of the magnetic memory illustrated inFIG. 18, taken on line “A-A′”. The configuration shown in these drawingscorresponds to a 1-bit memory cell included in the magnetic memory shownin FIG. 16 or FIG. 17. This memory cell includes a memory element part311 and an address selection transistor part 312.

The memory element part 311 includes the magneto-resistance effect film10 and a pair of wirings 322, 324 connected to the magneto-resistanceeffect film 10. The magneto-resistance effect film 10 is themagneto-resistance effect element (CCP-CPP element) as described in theabove embodiments.

Meanwhile, in the address selection transistor part 312, a transistor330 having connection therewith via a via 326 and an embedded wiring 328is provided. The transistor 330 performs switching operations inaccordance with voltages applied to a gate 332 to control theopening/closing of the current path between the magneto-resistanceeffect film 10 and the wiring 334.

Further, below the magneto-resistance effect film 10, a write wiring 323is provided in the direction substantially orthogonal to the wiring 322.These write wirings 322, 323 can be formed of, for example, aluminum(Al), copper (Cu), tungsten (W), tantalnum (Ta) or an alloy containingany of these elements.

In the memory cell of such a configuration, when writing bit informationinto the magneto-resistance effect element 10, a writing pulse currentis flowed in the wirings 322, 323, and a synthetic magnetic fieldinduced by the writing current is applied to appropriately invert themagnetization of a recording layer of the magneto-resistance effectelement 10.

Further, when reading out the bit information, a sense current is flowedthrough the magneto-resistance effect element 10 including the magneticrecording layer and a lower electrode 324 to measure a resistance valueof or a fluctuation in the resistance values of the magneto-resistanceeffect element 10.

The magnetic memory according to the embodiment can assure writing andreading by surely controlling the magnetic domain of the recording layereven though the cell is miniaturized in size, with the use of themagneto-resistance effect element (CCP-CPP element) according to theabove-described embodiment.

Another Embodiment

Although the present invention was described in detail with reference tothe above examples, this invention is not limited to the abovedisclosure and every kind of variation and modification may be madewithout departing from the scope of the present invention.

The concrete structure of the magneto-resistance effect element, and theshape and material of the electrodes, the magnetic field biasing filmsand the insulating layer can be appropriately selected among the oneswell known by the person skilled in the art. In these cases, theintended magneto-resistance effect element according to the presentinvention can be obtained so as to exhibit the same effect/function asdescribed above.

When the magneto-resistance effect element is applied for a reproducingmagnetic head, the detecting resolution of the magnetic head can bedefined by applying magnetic shielding for the upper side and the lowerside of the magneto-resistance effect element. Moreover, themagneto-resistance effect element can be applied for both of alongitudinal magnetic recording type magnetic head and a verticalmagnetic recording type magnetic recording type magnetic head. Also, themagneto-resistance effect element can be applied for both of alongitudinal magnetic recording/reproducing device and a verticalmagnetic recording/reproducing device. The magneticrecording/reproducing device may be a so-called stationary type magneticdevice where a specific recording medium is installed therein or aso-called removable type magnetic device where a recording medium can bereplaced.

1. A magneto-resistance effect element, comprising: a first magneticlayer; a first metallic layer, which is formed on said first magneticlayer, mainly containing an element selected from the group consistingof Cu, Au, Ag; a functional layer, which is formed on said firstmetallic layer, mainly containing an element selected from the groupconsisting of Si, Hf, Ti, Mo, W, Nb, Mg, Cr and Zr; a current confinedlayer including an insulating layer and a current path which are made bymeans of oxidizing, nitriding or oxynitiriding for a second metalliclayer, mainly containing Al, formed on said functional layer; and asecond magnetic layer which is formed on said current confined layer. 2.A magneto-resistance effect element, comprising: a first magnetic layer;a first metallic layer, which is formed on said first magnetic layer,mainly containing an element selected from the group consisting of Cu,Au, Ag; a current confined layer including an insulating layer and acurrent path which are made by means of oxidizing, nitriding oroxynitiriding for a second metallic layer, mainly containing Al, formedon said first metallic layer; a functional layer, which is formed onsaid current confined layer, mainly containing an element selected fromthe group consisting of Si, Hf, Ti, Mo, W, Nb, Mg, Cr and Zr; and asecond magnetic layer which is formed on said functional layer.
 3. Amagneto-resistance effect element, comprising: a first magnetic layer; afirst metallic layer, which is formed on said first magnetic layer,mainly containing an element selected from the group consisting of Cu,Au, Ag; a first functional layer, which is formed on said first metalliclayer, mainly containing an element selected from the group consistingof Si, Hf, Ti, Mo, W, Nb, Mg, Cr and Zr; a current confined layerincluding an insulating layer and a current path which are made by meansof oxidizing, nitriding or oxynitiriding for a second metallic layer,mainly containing Al, formed on said first functional layer; a secondfunctional layer, which is formed on said current confined layer, mainlycontaining an element selected from the group consisting of Si, Hf, Ti,Mo, W, Nb, Mg, Cr and Zr; and a second magnetic layer which is formed onsaid second functional layer.
 4. A magneto-resistance effect element,comprising: a first magnetic layer; a first metallic layer which isformed on said first magnetic layer; a functional layer which is formedon said first metallic layer; a current confined layer including aninsulating layer and a current path which are made by means ofoxidizing, nitriding or oxynitiriding for a second metallic layer formedon said functional layer; and a second magnetic layer which is formed onsaid current confined layer, wherein said functional layer mainlycontains an element with an oxide-nitride formation energy lower than anoxide-nitride formation energy of an element mainly composing said firstmetallic layer and higher than an oxide-nitride formation energy of anelement mainly composing said second metallic layer.
 5. Amagneto-resistance effect element, comprising: a first magnetic layer; afirst metallic layer which is formed on said first magnetic layer; acurrent confined layer including an insulating layer and a current pathwhich are made by means of oxidizing, nitriding or oxynitiriding for asecond metallic layer formed on said functional layer; a functionallayer which is formed on said current confined layer; and a secondmagnetic layer which is formed on said functional layer, wherein saidfunctional layer mainly contains an element with an oxide-nitrideformation energy lower than an oxide-nitride formation energy of anelement mainly composing said second magnetic layer and higher than anoxide-nitride formation energy of an element mainly composing saidsecond metallic layer.
 6. A magneto-resistance effect element,comprising: a first magnetic layer; a first metallic layer which isformed on said first magnetic layer; a first functional layer which isformed on said first metallic layer; a current confined layer includingan insulating layer and a current path which are made by means ofoxidizing, nitriding or oxynitiriding for a second metallic layer formedon said first functional layer; a second functional layer which isformed on said current confined layer; and a second magnetic layer whichis formed on said second functional layer, wherein said first functionallayer mainly contains an element with an oxide-nitride formation energylower than an oxide-nitride formation energy of an element mainlycomposing said first metallic layer and higher than an oxide-nitrideformation energy of an element mainly composing said second metalliclayer; and wherein said second functional layer mainly contains anelement with an oxide-nitride formation energy lower than anoxide-nitride formation energy of an element mainly composing said firstmagnetic layer and higher than an oxide-nitride formation energy of anelement mainly composing said second metallic layer.
 7. A magnetic head,comprising a magneto-resistance effect element as set forth in claim 1.8. A magnetic head, comprising a magneto-resistance effect element asset forth in claim
 2. 9. A magnetic head, comprising amagneto-resistance effect element as set forth in claim
 3. 10. Amagnetic recording/reproducing device, comprising a magnetic head as setforth in claim 7 and a magnetic recording medium.
 11. A magneticrecording/reproducing device, comprising a magnetic head as set forth inclaim 8 and a magnetic recording medium.
 12. A magneticrecording/reproducing device, comprising a magnetic head as set forth inclaim 9 and a magnetic recording medium.
 13. A magnetic memory,comprising a magneto-resistance effect element as set forth in claim 1.14. A magnetic memory, comprising a magneto-resistance effect element asset forth in claim
 2. 15. A magnetic memory, comprising amagneto-resistance effect element as set forth in claim 3.